Bump version to 2.3.14

* fix: verify audience claim

Co-Authored-By: Vladimir Pouzanov <farcaller@gmail.com>
Signed-off-by: CI <350466+crenshaw-dev@users.noreply.github.com>

* fix unit tests

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

* fix lint

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

* go mod tidy

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

* handle single aud claim marshaled as a string

Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>

Signed-off-by: CI <350466+crenshaw-dev@users.noreply.github.com>
Signed-off-by: Michael Crenshaw <350466+crenshaw-dev@users.noreply.github.com>
Co-authored-by: CI <350466+crenshaw-dev@users.noreply.github.com>
Co-authored-by: Vladimir Pouzanov <farcaller@gmail.com>

.github/workflows/image.yaml

@@ -61,7 +61,7 @@ jobs:
             IMAGE_PLATFORMS=linux/amd64,linux/arm64
           fi
           echo "Building image for platforms: $IMAGE_PLATFORMS"
-          docker buildx build --platform $IMAGE_PLATFORMS --push="${{ github.event_name == 'push' }}" \
+          docker buildx build --platform $IMAGE_PLATFORMS --sbom=false --provenance=false --push="${{ github.event_name == 'push' }}" \
             -t ghcr.io/argoproj/argocd:${{ steps.image.outputs.tag }} \
             -t quay.io/argoproj/argocd:latest .
         working-directory: ./src/github.com/argoproj/argo-cd

.github/workflows/release.yaml

@@ -208,7 +208,7 @@ jobs:
           set -ue
           git clean -fd
           mkdir -p dist/
-          docker buildx build --platform linux/amd64,linux/arm64 --push -t ${IMAGE_NAMESPACE}/argocd:v${TARGET_VERSION} -t argoproj/argocd:v${TARGET_VERSION} .
+          docker buildx build --platform linux/amd64,linux/arm64 --sbom=false --provenance=false --push -t ${IMAGE_NAMESPACE}/argocd:v${TARGET_VERSION} -t argoproj/argocd:v${TARGET_VERSION} .
           make release-cli
           make checksums
           chmod +x ./dist/argocd-linux-amd64

VERSION

@@ -1 +1 @@
-2.3.13
+2.3.14

cmd/argocd/commands/admin/settings.go

@@ -207,7 +207,7 @@ var validatorsByGroup = map[string]settingValidator{
 			}
 			ssoProvider = "Dex"
 		} else if general.OIDCConfigRAW != "" {
-			if _, err := settings.UnmarshalOIDCConfig(general.OIDCConfigRAW); err != nil {
+			if err := settings.ValidateOIDCConfig(general.OIDCConfigRAW); err != nil {
 				return "", fmt.Errorf("invalid oidc.config: %v", err)
 			}
 			ssoProvider = "OIDC"

common/common.go

@@ -1,6 +1,7 @@
 package common
 
 import (
+	"errors"
 	"os"
 	"time"
 )
@@ -241,3 +242,8 @@ func GetPluginSockFilePath() string {
 		return pluginSockFilePath
 	}
 }
+
+// Common error messages
+const TokenVerificationError = "failed to verify the token"
+
+var TokenVerificationErr = errors.New(TokenVerificationError)

docs/operator-manual/user-management/index.md

@@ -300,6 +300,18 @@ data:
     issuer: https://dev-123456.oktapreview.com
     clientID: aaaabbbbccccddddeee
     clientSecret: $oidc.okta.clientSecret
+    
+    # Optional list of allowed aud claims. If omitted or empty, defaults to the clientID value above. If you specify a 
+    # list and want the clientD to be allowed, you must explicitly include it in the list.
+    # Token verification will pass if any of the token's audiences matches any of the audiences in this list.
+    allowedAudiences:
+    - aaaabbbbccccddddeee
+    - qqqqwwwweeeerrrrttt
+
+    # Optional. If false, tokens without an audience will always fail validation. If true, tokens without an audience 
+    # will always pass validation.
+    # Defaults to true for Argo CD < 2.6.0. Defaults to false for Argo CD >= 2.6.0.
+    skipAudienceCheckWhenTokenHasNoAudience: true
 
     # Optional set of OIDC scopes to request. If omitted, defaults to: ["openid", "profile", "email", "groups"]
     requestedScopes: ["openid", "profile", "email", "groups"]

go.mod

@@ -200,7 +200,7 @@ require (
 	gopkg.in/alexcesaro/quotedprintable.v3 v3.0.0-20150716171945-2caba252f4dc // indirect
 	gopkg.in/gomail.v2 v2.0.0-20160411212932-81ebce5c23df // indirect
 	gopkg.in/inf.v0 v0.9.1 // indirect
-	gopkg.in/square/go-jose.v2 v2.2.2 // indirect
+	gopkg.in/square/go-jose.v2 v2.2.2
 	gopkg.in/warnings.v0 v0.1.2 // indirect
 	gopkg.in/yaml.v3 v3.0.0-20210107192922-496545a6307b // indirect
 	k8s.io/apiserver v0.23.1

manifests/base/kustomization.yaml

@@ -5,7 +5,7 @@ kind: Kustomization
 images:
 - name: quay.io/argoproj/argocd
   newName: quay.io/argoproj/argocd
-  newTag: v2.3.13
+  newTag: v2.3.14
 resources:
 - ./application-controller
 - ./dex

manifests/core-install.yaml

@@ -9698,7 +9698,7 @@ spec:
           value: /helm-working-dir
         - name: HELM_DATA_HOME
           value: /helm-working-dir
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         livenessProbe:
           failureThreshold: 3
@@ -9747,7 +9747,7 @@ spec:
         - -n
         - /usr/local/bin/argocd
         - /var/run/argocd/argocd-cmp-server
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         name: copyutil
         volumeMounts:
         - mountPath: /var/run/argocd
@@ -9912,7 +9912,7 @@ spec:
               key: controller.default.cache.expiration
               name: argocd-cmd-params-cm
               optional: true
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         livenessProbe:
           httpGet:

manifests/core-install/kustomization.yaml

@@ -11,4 +11,4 @@ resources:
 images:
 - name: quay.io/argoproj/argocd
   newName: quay.io/argoproj/argocd
-  newTag: v2.3.13
+  newTag: v2.3.14

manifests/ha/base/kustomization.yaml

@@ -11,7 +11,7 @@ patchesStrategicMerge:
 images:
 - name: quay.io/argoproj/argocd
   newName: quay.io/argoproj/argocd
-  newTag: v2.3.13
+  newTag: v2.3.14
 resources:
 - ../../base/application-controller
 - ../../base/dex

manifests/ha/install.yaml

@@ -10516,7 +10516,7 @@ spec:
         - -n
         - /usr/local/bin/argocd
         - /shared/argocd-dex
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         name: copyutil
         volumeMounts:
@@ -10549,7 +10549,7 @@ spec:
       containers:
       - command:
         - argocd-notifications
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         livenessProbe:
           tcpSocket:
@@ -10788,7 +10788,7 @@ spec:
           value: /helm-working-dir
         - name: HELM_DATA_HOME
           value: /helm-working-dir
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         livenessProbe:
           failureThreshold: 3
@@ -10837,7 +10837,7 @@ spec:
         - -n
         - /usr/local/bin/argocd
         - /var/run/argocd/argocd-cmp-server
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         name: copyutil
         volumeMounts:
         - mountPath: /var/run/argocd
@@ -11064,7 +11064,7 @@ spec:
               key: server.http.cookie.maxnumber
               name: argocd-cmd-params-cm
               optional: true
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         livenessProbe:
           httpGet:
@@ -11260,7 +11260,7 @@ spec:
               key: controller.default.cache.expiration
               name: argocd-cmd-params-cm
               optional: true
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         livenessProbe:
           httpGet:

manifests/ha/namespace-install.yaml

@@ -7812,7 +7812,7 @@ spec:
         - -n
         - /usr/local/bin/argocd
         - /shared/argocd-dex
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         name: copyutil
         volumeMounts:
@@ -7845,7 +7845,7 @@ spec:
       containers:
       - command:
         - argocd-notifications
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         livenessProbe:
           tcpSocket:
@@ -8084,7 +8084,7 @@ spec:
           value: /helm-working-dir
         - name: HELM_DATA_HOME
           value: /helm-working-dir
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         livenessProbe:
           failureThreshold: 3
@@ -8133,7 +8133,7 @@ spec:
         - -n
         - /usr/local/bin/argocd
         - /var/run/argocd/argocd-cmp-server
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         name: copyutil
         volumeMounts:
         - mountPath: /var/run/argocd
@@ -8360,7 +8360,7 @@ spec:
               key: server.http.cookie.maxnumber
               name: argocd-cmd-params-cm
               optional: true
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         livenessProbe:
           httpGet:
@@ -8556,7 +8556,7 @@ spec:
               key: controller.default.cache.expiration
               name: argocd-cmd-params-cm
               optional: true
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         livenessProbe:
           httpGet:

manifests/install.yaml

@@ -9886,7 +9886,7 @@ spec:
         - -n
         - /usr/local/bin/argocd
         - /shared/argocd-dex
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         name: copyutil
         volumeMounts:
@@ -9919,7 +9919,7 @@ spec:
       containers:
       - command:
         - argocd-notifications
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         livenessProbe:
           tcpSocket:
@@ -10122,7 +10122,7 @@ spec:
           value: /helm-working-dir
         - name: HELM_DATA_HOME
           value: /helm-working-dir
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         livenessProbe:
           failureThreshold: 3
@@ -10171,7 +10171,7 @@ spec:
         - -n
         - /usr/local/bin/argocd
         - /var/run/argocd/argocd-cmp-server
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         name: copyutil
         volumeMounts:
         - mountPath: /var/run/argocd
@@ -10394,7 +10394,7 @@ spec:
               key: server.http.cookie.maxnumber
               name: argocd-cmd-params-cm
               optional: true
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         livenessProbe:
           httpGet:
@@ -10584,7 +10584,7 @@ spec:
               key: controller.default.cache.expiration
               name: argocd-cmd-params-cm
               optional: true
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         livenessProbe:
           httpGet:

manifests/namespace-install.yaml

@@ -7182,7 +7182,7 @@ spec:
         - -n
         - /usr/local/bin/argocd
         - /shared/argocd-dex
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         name: copyutil
         volumeMounts:
@@ -7215,7 +7215,7 @@ spec:
       containers:
       - command:
         - argocd-notifications
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         livenessProbe:
           tcpSocket:
@@ -7418,7 +7418,7 @@ spec:
           value: /helm-working-dir
         - name: HELM_DATA_HOME
           value: /helm-working-dir
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         livenessProbe:
           failureThreshold: 3
@@ -7467,7 +7467,7 @@ spec:
         - -n
         - /usr/local/bin/argocd
         - /var/run/argocd/argocd-cmp-server
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         name: copyutil
         volumeMounts:
         - mountPath: /var/run/argocd
@@ -7690,7 +7690,7 @@ spec:
               key: server.http.cookie.maxnumber
               name: argocd-cmd-params-cm
               optional: true
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         livenessProbe:
           httpGet:
@@ -7880,7 +7880,7 @@ spec:
               key: controller.default.cache.expiration
               name: argocd-cmd-params-cm
               optional: true
-        image: quay.io/argoproj/argocd:v2.3.13
+        image: quay.io/argoproj/argocd:v2.3.14
         imagePullPolicy: Always
         livenessProbe:
           httpGet:

server/server_test.go

@@ -32,6 +32,7 @@ import (
 	appstatecache "github.com/argoproj/argo-cd/v2/util/cache/appstate"
 	"github.com/argoproj/argo-cd/v2/util/rbac"
 	settings_util "github.com/argoproj/argo-cd/v2/util/settings"
+	testutil "github.com/argoproj/argo-cd/v2/util/test"
 )
 
 func fakeServer() (*ArgoCDServer, func()) {
@@ -500,7 +501,7 @@ func dexMockHandler(t *testing.T, url string) func(http.ResponseWriter, *http.Re
 	}
 }
 
-func getTestServer(t *testing.T, anonymousEnabled bool, withFakeSSO bool) (argocd *ArgoCDServer, dexURL string) {
+func getTestServer(t *testing.T, anonymousEnabled bool, withFakeSSO bool, useDexForSSO bool) (argocd *ArgoCDServer, oidcURL string) {
 	cm := test.NewFakeConfigMap()
 	if anonymousEnabled {
 		cm.Data["users.anonymous.enabled"] = "true"
@@ -511,9 +512,14 @@ func getTestServer(t *testing.T, anonymousEnabled bool, withFakeSSO bool) (argoc
 	ts.Config.Handler = http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		dexMockHandler(t, ts.URL)(w, r)
 	})
+	oidcServer := ts
+	if !useDexForSSO {
+		oidcServer = testutil.GetOIDCTestServer(t)
+	}
 	if withFakeSSO {
 		cm.Data["url"] = ts.URL
-		cm.Data["dex.config"] = `
+		if useDexForSSO {
+			cm.Data["dex.config"] = `
 connectors:
   # OIDC
   - type: OIDC
@@ -523,6 +529,19 @@ connectors:
     issuer: https://auth.example.gom
     clientID: test-client
     clientSecret: $dex.oidc.clientSecret`
+		} else {
+			oidcConfig := settings_util.OIDCConfig{
+				Name:         "Okta",
+				Issuer:       oidcServer.URL,
+				ClientID:     "argo-cd",
+				ClientSecret: "$oidc.okta.clientSecret",
+			}
+			oidcConfigString, err := yaml.Marshal(oidcConfig)
+			require.NoError(t, err)
+			cm.Data["oidc.config"] = string(oidcConfigString)
+			// Avoid bothering with certs for local tests.
+			cm.Data["oidc.tls.insecure.skip.verify"] = "true"
+		}
 	}
 	secret := test.NewFakeSecret()
 	kubeclientset := fake.NewSimpleClientset(cm, secret)
@@ -532,27 +551,32 @@ connectors:
 		KubeClientset: kubeclientset,
 		AppClientset:  appClientSet,
 	}
-	if withFakeSSO {
+	if withFakeSSO && useDexForSSO {
 		argoCDOpts.DexServerAddr = ts.URL
 	}
 	argocd = NewServer(context.Background(), argoCDOpts)
-	return argocd, ts.URL
+	return argocd, oidcServer.URL
 }
 
 func TestAuthenticate_3rd_party_JWTs(t *testing.T) {
+	// Marshaling single strings to strings is typical, so we test for this relatively common behavior.
+	jwt.MarshalSingleStringAsArray = false
+
 	type testData struct {
 		test                  string
 		anonymousEnabled      bool
 		claims                jwt.RegisteredClaims
 		expectedErrorContains string
 		expectedClaims        interface{}
+		useDex                bool
 	}
 	var tests = []testData{
+		// Dex
 		{
 			test:                  "anonymous disabled, no audience",
 			anonymousEnabled:      false,
-			claims:                jwt.RegisteredClaims{},
-			expectedErrorContains: "no audience found in the token",
+			claims:                jwt.RegisteredClaims{ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))},
+			expectedErrorContains: common.TokenVerificationError,
 			expectedClaims:        nil,
 		},
 		{
@@ -565,31 +589,95 @@ func TestAuthenticate_3rd_party_JWTs(t *testing.T) {
 		{
 			test:                  "anonymous disabled, unexpired token, admin claim",
 			anonymousEnabled:      false,
-			claims:                jwt.RegisteredClaims{Audience: jwt.ClaimStrings{"test-client"}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))},
-			expectedErrorContains: "id token signed with unsupported algorithm",
+			claims:                jwt.RegisteredClaims{Audience: jwt.ClaimStrings{common.ArgoCDClientAppID}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))},
+			expectedErrorContains: common.TokenVerificationError,
 			expectedClaims:        nil,
 		},
 		{
 			test:                  "anonymous enabled, unexpired token, admin claim",
 			anonymousEnabled:      true,
-			claims:                jwt.RegisteredClaims{Audience: jwt.ClaimStrings{"test-client"}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))},
+			claims:                jwt.RegisteredClaims{Audience: jwt.ClaimStrings{common.ArgoCDClientAppID}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))},
 			expectedErrorContains: "",
 			expectedClaims:        "",
 		},
 		{
 			test:                  "anonymous disabled, expired token, admin claim",
 			anonymousEnabled:      false,
-			claims:                jwt.RegisteredClaims{Audience: jwt.ClaimStrings{"test-client"}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now())},
-			expectedErrorContains: "token is expired",
-			expectedClaims:        jwt.RegisteredClaims{Issuer:"sso"},
+			claims:                jwt.RegisteredClaims{Audience: jwt.ClaimStrings{common.ArgoCDClientAppID}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now())},
+			expectedErrorContains: common.TokenVerificationError,
+			expectedClaims:        jwt.RegisteredClaims{Issuer: "sso"},
 		},
 		{
 			test:                  "anonymous enabled, expired token, admin claim",
 			anonymousEnabled:      true,
-			claims:                jwt.RegisteredClaims{Audience: jwt.ClaimStrings{"test-client"}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now())},
+			claims:                jwt.RegisteredClaims{Audience: jwt.ClaimStrings{common.ArgoCDClientAppID}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now())},
 			expectedErrorContains: "",
 			expectedClaims:        "",
 		},
+		{
+			test:                  "anonymous disabled, unexpired token, admin claim, incorrect audience",
+			anonymousEnabled:      false,
+			claims:                jwt.RegisteredClaims{Audience: jwt.ClaimStrings{"incorrect-audience"}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))},
+			expectedErrorContains: common.TokenVerificationError,
+			expectedClaims:        nil,
+		},
+		// External OIDC (not bundled Dex)
+		{
+			test:                  "external OIDC: anonymous disabled, no audience",
+			anonymousEnabled:      false,
+			claims:                jwt.RegisteredClaims{ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))},
+			useDex:                true,
+			expectedErrorContains: common.TokenVerificationError,
+			expectedClaims:        nil,
+		},
+		{
+			test:                  "external OIDC: anonymous enabled, no audience",
+			anonymousEnabled:      true,
+			claims:                jwt.RegisteredClaims{},
+			useDex:                true,
+			expectedErrorContains: "",
+			expectedClaims:        "",
+		},
+		{
+			test:                  "external OIDC: anonymous disabled, unexpired token, admin claim",
+			anonymousEnabled:      false,
+			claims:                jwt.RegisteredClaims{Audience: jwt.ClaimStrings{common.ArgoCDClientAppID}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))},
+			useDex:                true,
+			expectedErrorContains: common.TokenVerificationError,
+			expectedClaims:        nil,
+		},
+		{
+			test:                  "external OIDC: anonymous enabled, unexpired token, admin claim",
+			anonymousEnabled:      true,
+			claims:                jwt.RegisteredClaims{Audience: jwt.ClaimStrings{common.ArgoCDClientAppID}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))},
+			useDex:                true,
+			expectedErrorContains: "",
+			expectedClaims:        "",
+		},
+		{
+			test:                  "external OIDC: anonymous disabled, expired token, admin claim",
+			anonymousEnabled:      false,
+			claims:                jwt.RegisteredClaims{Audience: jwt.ClaimStrings{common.ArgoCDClientAppID}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now())},
+			useDex:                true,
+			expectedErrorContains: common.TokenVerificationError,
+			expectedClaims:        jwt.RegisteredClaims{Issuer: "sso"},
+		},
+		{
+			test:                  "external OIDC: anonymous enabled, expired token, admin claim",
+			anonymousEnabled:      true,
+			claims:                jwt.RegisteredClaims{Audience: jwt.ClaimStrings{common.ArgoCDClientAppID}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now())},
+			useDex:                true,
+			expectedErrorContains: "",
+			expectedClaims:        "",
+		},
+		{
+			test:                  "external OIDC: anonymous disabled, unexpired token, admin claim, incorrect audience",
+			anonymousEnabled:      false,
+			claims:                jwt.RegisteredClaims{Audience: jwt.ClaimStrings{"incorrect-audience"}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))},
+			useDex:                true,
+			expectedErrorContains: common.TokenVerificationError,
+			expectedClaims:        nil,
+		},
 	}
 
 	for _, testData := range tests {
@@ -599,10 +687,15 @@ func TestAuthenticate_3rd_party_JWTs(t *testing.T) {
 			t.Parallel()
 
 			// Must be declared here to avoid race.
-			ctx := context.Background()  //nolint:ineffassign,staticcheck
+			ctx := context.Background() //nolint:ineffassign,staticcheck
 
-			argocd, dexURL := getTestServer(t, testDataCopy.anonymousEnabled, true)
-			testDataCopy.claims.Issuer = fmt.Sprintf("%s/api/dex", dexURL)
+			argocd, oidcURL := getTestServer(t, testDataCopy.anonymousEnabled, true, testDataCopy.useDex)
+
+			if testDataCopy.useDex {
+				testDataCopy.claims.Issuer = fmt.Sprintf("%s/api/dex", oidcURL)
+			} else {
+				testDataCopy.claims.Issuer = oidcURL
+			}
 			token := jwt.NewWithClaims(jwt.SigningMethodHS256, testDataCopy.claims)
 			tokenString, err := token.SignedString([]byte("key"))
 			require.NoError(t, err)
@@ -653,7 +746,7 @@ func TestAuthenticate_no_request_metadata(t *testing.T) {
 		t.Run(testDataCopy.test, func(t *testing.T) {
 			t.Parallel()
 
-			argocd, _ := getTestServer(t, testDataCopy.anonymousEnabled, true)
+			argocd, _ := getTestServer(t, testDataCopy.anonymousEnabled, true, true)
 			ctx := context.Background()
 
 			ctx, err := argocd.Authenticate(ctx)
@@ -698,9 +791,9 @@ func TestAuthenticate_no_SSO(t *testing.T) {
 			t.Parallel()
 
 			// Must be declared here to avoid race.
-			ctx := context.Background()  //nolint:ineffassign,staticcheck
+			ctx := context.Background() //nolint:ineffassign,staticcheck
 
-			argocd, dexURL := getTestServer(t, testDataCopy.anonymousEnabled, false)
+			argocd, dexURL := getTestServer(t, testDataCopy.anonymousEnabled, false, true)
 			token := jwt.NewWithClaims(jwt.SigningMethodHS256, jwt.RegisteredClaims{Issuer: fmt.Sprintf("%s/api/dex", dexURL)})
 			tokenString, err := token.SignedString([]byte("key"))
 			require.NoError(t, err)
@@ -774,7 +867,7 @@ func TestAuthenticate_bad_request_metadata(t *testing.T) {
 			test:                 "anonymous disabled, bad auth header",
 			anonymousEnabled:     false,
 			metadata:             metadata.MD{"authorization": []string{"Bearer eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJhZG1pbiJ9.TGGTTHuuGpEU8WgobXxkrBtW3NiR3dgw5LR-1DEW3BQ"}},
-			expectedErrorMessage: "no audience found in the token",
+			expectedErrorMessage: common.TokenVerificationError,
 			expectedClaims:       nil,
 		},
 		{
@@ -788,7 +881,7 @@ func TestAuthenticate_bad_request_metadata(t *testing.T) {
 			test:                 "anonymous disabled, bad auth cookie",
 			anonymousEnabled:     false,
 			metadata:             metadata.MD{"grpcgateway-cookie": []string{"argocd.token=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJzdWIiOiJhZG1pbiJ9.TGGTTHuuGpEU8WgobXxkrBtW3NiR3dgw5LR-1DEW3BQ"}},
-			expectedErrorMessage: "no audience found in the token",
+			expectedErrorMessage: common.TokenVerificationError,
 			expectedClaims:       nil,
 		},
 		{
@@ -807,9 +900,9 @@ func TestAuthenticate_bad_request_metadata(t *testing.T) {
 			t.Parallel()
 
 			// Must be declared here to avoid race.
-			ctx := context.Background()  //nolint:ineffassign,staticcheck
+			ctx := context.Background() //nolint:ineffassign,staticcheck
 
-			argocd, _ := getTestServer(t, testDataCopy.anonymousEnabled, true)
+			argocd, _ := getTestServer(t, testDataCopy.anonymousEnabled, true, true)
 			ctx = metadata.NewIncomingContext(context.Background(), testDataCopy.metadata)
 
 			ctx, err := argocd.Authenticate(ctx)

util/oidc/oidc.go

@@ -348,9 +348,12 @@ func (a *ClientApp) HandleCallback(w http.ResponseWriter, r *http.Request) {
 		http.Error(w, "no id_token in token response", http.StatusInternalServerError)
 		return
 	}
-	idToken, err := a.provider.Verify(a.clientID, idTokenRAW)
+
+	idToken, err := a.provider.Verify(idTokenRAW, a.settings)
+
 	if err != nil {
-		http.Error(w, fmt.Sprintf("invalid session token: %v", err), http.StatusInternalServerError)
+		log.Warnf("Failed to verify token: %s", err)
+		http.Error(w, common.TokenVerificationError, http.StatusInternalServerError)
 		return
 	}
 	path := "/"

util/oidc/oidc_test.go

@@ -89,7 +89,7 @@ func (p *fakeProvider) ParseConfig() (*OIDCConfiguration, error) {
 	return nil, nil
 }
 
-func (p *fakeProvider) Verify(_, _ string) (*gooidc.IDToken, error) {
+func (p *fakeProvider) Verify(_ string, _ *settings.ArgoCDSettings) (*gooidc.IDToken, error) {
 	return nil, nil
 }
 

util/oidc/provider.go

@@ -2,6 +2,7 @@ package oidc
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"net/http"
 	"strings"
@@ -9,8 +10,13 @@ import (
 	gooidc "github.com/coreos/go-oidc"
 	log "github.com/sirupsen/logrus"
 	"golang.org/x/oauth2"
+
+	"github.com/argoproj/argo-cd/v2/util/security"
+	"github.com/argoproj/argo-cd/v2/util/settings"
 )
 
+var ErrTokenExpired = errors.New("token is expired")
+
 // Provider is a wrapper around go-oidc provider to also provide the following features:
 // 1. lazy initialization/querying of the provider
 // 2. automatic detection of change in signing keys
@@ -23,7 +29,7 @@ type Provider interface {
 
 	ParseConfig() (*OIDCConfiguration, error)
 
-	Verify(clientID, tokenString string) (*gooidc.IDToken, error)
+	Verify(tokenString string, argoSettings *settings.ArgoCDSettings) (*gooidc.IDToken, error)
 }
 
 type providerImpl struct {
@@ -69,13 +75,64 @@ func (p *providerImpl) newGoOIDCProvider() (*gooidc.Provider, error) {
 	return prov, nil
 }
 
-func (p *providerImpl) Verify(clientID, tokenString string) (*gooidc.IDToken, error) {
+func (p *providerImpl) Verify(tokenString string, argoSettings *settings.ArgoCDSettings) (*gooidc.IDToken, error) {
+	// According to the JWT spec, the aud claim is optional. The spec also says (emphasis mine):
+	//
+	//   If the principal processing the claim does not identify itself with a value in the "aud" claim _when this
+	//   claim is present_, then the JWT MUST be rejected.
+	//
+	//     - https://www.rfc-editor.org/rfc/rfc7519#section-4.1.3
+	//
+	// If the claim is not present, we can skip the audience claim check (called the "ClientID check" in go-oidc's
+	// terminology).
+	//
+	// The OIDC spec says that the aud claim is required (https://openid.net/specs/openid-connect-core-1_0.html#IDToken).
+	// But we cannot assume that all OIDC providers will follow the spec. For Argo CD <2.6.0, we will default to
+	// allowing the aud claim to be optional. In Argo CD >=2.6.0, we will default to requiring the aud claim to be
+	// present and give users the skipAudienceCheckWhenTokenHasNoAudience setting to revert the behavior if necessary.
+	//
+	// At this point, we have not verified that the token has not been altered. All code paths below MUST VERIFY
+	// THE TOKEN SIGNATURE to confirm that an attacker did not maliciously remove the "aud" claim.
+	unverifiedHasAudClaim, err := security.UnverifiedHasAudClaim(tokenString)
+	if err != nil {
+		return nil, fmt.Errorf("failed to determine whether the token has an aud claim: %w", err)
+	}
+
+	var idToken *gooidc.IDToken
+	if !unverifiedHasAudClaim {
+		idToken, err = p.verify("", tokenString, argoSettings.SkipAudienceCheckWhenTokenHasNoAudience())
+	} else {
+		allowedAudiences := argoSettings.OAuth2AllowedAudiences()
+		if len(allowedAudiences) == 0 {
+			return nil, errors.New("token has an audience claim, but no allowed audiences are configured")
+		}
+		// Token must be verified for at least one allowed audience
+		for _, aud := range allowedAudiences {
+			idToken, err = p.verify(aud, tokenString, false)
+			if err == nil {
+				break
+			}
+		}
+	}
+
+	if err != nil {
+		if strings.HasPrefix(err.Error(), "oidc: token is expired") {
+			return nil, ErrTokenExpired
+		}
+		return nil, fmt.Errorf("failed to verify token: %w", err)
+	}
+
+	return idToken, nil
+}
+
+func (p *providerImpl) verify(clientID, tokenString string, skipClientIDCheck bool) (*gooidc.IDToken, error) {
 	ctx := context.Background()
 	prov, err := p.provider()
 	if err != nil {
 		return nil, err
 	}
-	verifier := prov.Verifier(&gooidc.Config{ClientID: clientID})
+	config := &gooidc.Config{ClientID: clientID, SkipClientIDCheck: skipClientIDCheck}
+	verifier := prov.Verifier(config)
 	idToken, err := verifier.Verify(ctx, tokenString)
 	if err != nil {
 		// HACK: if we failed token verification, it's possible the reason was because dex
@@ -93,7 +150,7 @@ func (p *providerImpl) Verify(clientID, tokenString string) (*gooidc.IDToken, er
 			// return original error if we fail to re-initialize OIDC
 			return nil, err
 		}
-		verifier = newProvider.Verifier(&gooidc.Config{ClientID: clientID})
+		verifier = newProvider.Verifier(config)
 		idToken, err = verifier.Verify(ctx, tokenString)
 		if err != nil {
 			return nil, err

util/security/jwt.go

@@ -0,0 +1,80 @@
+package security
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"fmt"
+	"strings"
+)
+
+// parseJWT parses a jwt and returns it as json bytes.
+//
+// This function DOES NOT VERIFY THE TOKEN. You still have to verify the token to confirm that the token holder has not
+// altered the claims.
+//
+// This code is copied almost verbatim from go-oidc (https://github.com/coreos/go-oidc).
+func parseJWT(p string) ([]byte, error) {
+	parts := strings.Split(p, ".")
+	if len(parts) < 2 {
+		return nil, fmt.Errorf("malformed jwt, expected 3 parts got %d", len(parts))
+	}
+	payload, err := base64.RawURLEncoding.DecodeString(parts[1])
+	if err != nil {
+		return nil, fmt.Errorf("malformed jwt payload: %v", err)
+	}
+	return payload, nil
+}
+
+type audience []string
+
+// UnmarshalJSON allows us to unmarshal either a single audience or a list of audiences.
+// Taken from: https://github.com/coreos/go-oidc/blob/a8ceb9a2043fca2e43518633920db746808b1138/oidc/oidc.go#L475
+func (a *audience) UnmarshalJSON(b []byte) error {
+	var s string
+	if json.Unmarshal(b, &s) == nil {
+		*a = audience{s}
+		return nil
+	}
+	var auds []string
+	if err := json.Unmarshal(b, &auds); err != nil {
+		return err
+	}
+	*a = auds
+	return nil
+}
+
+// jwtWithOnlyAudClaim represents a jwt where only the "aud" claim is present. This struct allows us to unmarshal a jwt
+// and be confident that the only information retrieved from that jwt is the "aud" claim.
+type jwtWithOnlyAudClaim struct {
+	Aud audience `json:"aud"`
+}
+
+// getUnverifiedAudClaim gets the "aud" claim from a jwt.
+//
+// This function DOES NOT VERIFY THE TOKEN. You still have to verify the token to confirm that the token holder has not
+// altered the "aud" claim.
+//
+// This code is copied almost verbatim from go-oidc (https://github.com/coreos/go-oidc).
+func getUnverifiedAudClaim(rawIDToken string) ([]string, error) {
+	payload, err := parseJWT(rawIDToken)
+	if err != nil {
+		return nil, fmt.Errorf("malformed jwt: %v", err)
+	}
+	var token jwtWithOnlyAudClaim
+	if err = json.Unmarshal(payload, &token); err != nil {
+		return nil, fmt.Errorf("failed to unmarshal claims: %v", err)
+	}
+	return token.Aud, nil
+}
+
+// UnverifiedHasAudClaim returns whether the "aud" claim is present in the given JWT.
+//
+// This function DOES NOT VERIFY THE TOKEN. You still have to verify the token to confirm that the token holder has not
+// altered the "aud" claim.
+func UnverifiedHasAudClaim(rawIDToken string) (bool, error) {
+	aud, err := getUnverifiedAudClaim(rawIDToken)
+	if err != nil {
+		return false, fmt.Errorf("failed to determine whether token had an audience claim: %w", err)
+	}
+	return aud != nil, nil
+}

util/security/jwt_test.go

@@ -0,0 +1,56 @@
+package security
+
+import (
+	"testing"
+	"time"
+
+	"github.com/golang-jwt/jwt/v4"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	utiltest "github.com/argoproj/argo-cd/v2/util/test"
+)
+
+func Test_UnverifiedHasAudClaim(t *testing.T) {
+	tokenForAud := func(t *testing.T, aud jwt.ClaimStrings) string {
+		claims := jwt.RegisteredClaims{Audience: aud, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))}
+		token := jwt.NewWithClaims(jwt.SigningMethodRS512, claims)
+		key, err := jwt.ParseRSAPrivateKeyFromPEM(utiltest.PrivateKey)
+		require.NoError(t, err)
+		tokenString, err := token.SignedString(key)
+		require.NoError(t, err)
+		return tokenString
+	}
+
+	testCases := []struct {
+		name           string
+		aud            jwt.ClaimStrings
+		expectedHasAud bool
+	}{
+		{
+			name:           "no audience",
+			aud:            jwt.ClaimStrings{},
+			expectedHasAud: false,
+		},
+		{
+			name:           "one empty audience",
+			aud:            jwt.ClaimStrings{""},
+			expectedHasAud: true,
+		},
+		{
+			name:           "one non-empty audience",
+			aud:            jwt.ClaimStrings{"test"},
+			expectedHasAud: true,
+		},
+	}
+
+	for _, testCase := range testCases {
+		testCaseCopy := testCase
+		t.Run(testCaseCopy.name, func(t *testing.T) {
+			t.Parallel()
+			out, err := UnverifiedHasAudClaim(tokenForAud(t, testCaseCopy.aud))
+			require.NoError(t, err)
+			assert.Equal(t, testCaseCopy.expectedHasAud, out)
+		})
+	}
+}

util/session/sessionmanager.go

@@ -12,7 +12,6 @@ import (
 	"strings"
 	"time"
 
-	oidc "github.com/coreos/go-oidc"
 	"github.com/golang-jwt/jwt/v4"
 	"github.com/google/uuid"
 	log "github.com/sirupsen/logrus"
@@ -413,7 +412,7 @@ func (mgr *SessionManager) VerifyUsernamePassword(username string, password stri
 			// introduces random delay to protect from timing-based user enumeration attack
 			delayNanoseconds := verificationDelayNoiseMin.Nanoseconds() +
 				int64(rand.Intn(int(verificationDelayNoiseMax.Nanoseconds()-verificationDelayNoiseMin.Nanoseconds())))
-				// take into account amount of time spent since the request start
+			// take into account amount of time spent since the request start
 			delayNanoseconds = delayNanoseconds - time.Since(start).Nanoseconds()
 			if delayNanoseconds > 0 {
 				mgr.sleep(time.Duration(delayNanoseconds))
@@ -477,31 +476,28 @@ func (mgr *SessionManager) VerifyToken(tokenString string) (jwt.Claims, string,
 			return nil, "", err
 		}
 
-		// Token must be verified for at least one audience
-		// TODO(jannfis): Is this the right way? Shouldn't we know our audience and only validate for the correct one?
-		var idToken *oidc.IDToken
-		for _, aud := range claims.Audience {
-			idToken, err = prov.Verify(aud, tokenString)
-			if err == nil {
-				break
-			}
+		argoSettings, err := mgr.settingsMgr.GetSettings()
+		if err != nil {
+			return nil, "", fmt.Errorf("cannot access settings while verifying the token: %w", err)
 		}
+		if argoSettings == nil {
+			return nil, "", fmt.Errorf("settings are not available while verifying the token")
+		}
+
+		idToken, err := prov.Verify(tokenString, argoSettings)
 
 		// The token verification has failed. If the token has expired, we will
 		// return a dummy claims only containing a value for the issuer, so the
 		// UI can handle expired tokens appropriately.
 		if err != nil {
-			if strings.HasPrefix(err.Error(), "oidc: token is expired") {
+			log.Warnf("Failed to verify token: %s", err)
+			if errors.Is(err, oidcutil.ErrTokenExpired) {
 				claims = jwt.RegisteredClaims{
 					Issuer: "sso",
 				}
-				return claims, "", err
+				return claims, "", common.TokenVerificationErr
 			}
-			return nil, "", err
-		}
-
-		if idToken == nil {
-			return nil, "", fmt.Errorf("no audience found in the token")
+			return nil, "", common.TokenVerificationErr
 		}
 
 		var claims jwt.MapClaims

util/session/sessionmanager_test.go

@@ -559,9 +559,7 @@ rootCA: |
 
 		_, _, err = mgr.VerifyToken(tokenString)
 		require.Error(t, err)
-		if !strings.Contains(err.Error(), "certificate signed by unknown authority") && !strings.Contains(err.Error(), "certificate is not trusted") {
-			t.Fatal("did not receive expected certificate verification failure error")
-		}
+		assert.ErrorIs(t, err, common.TokenVerificationErr)
 	})
 
 	t.Run("OIDC provider is external, TLS is configured", func(t *testing.T) {
@@ -596,9 +594,7 @@ requestedScopes: ["oidc"]`, oidcTestServer.URL),
 
 		_, _, err = mgr.VerifyToken(tokenString)
 		require.Error(t, err)
-		if !strings.Contains(err.Error(), "certificate signed by unknown authority") && !strings.Contains(err.Error(), "certificate is not trusted") {
-			t.Fatal("did not receive expected certificate verification failure error")
-		}
+		assert.ErrorIs(t, err, common.TokenVerificationErr)
 	})
 
 	t.Run("OIDC provider is Dex, TLS is configured", func(t *testing.T) {
@@ -633,9 +629,7 @@ requestedScopes: ["oidc"]`, oidcTestServer.URL),
 
 		_, _, err = mgr.VerifyToken(tokenString)
 		require.Error(t, err)
-		if !strings.Contains(err.Error(), "certificate signed by unknown authority") && !strings.Contains(err.Error(), "certificate is not trusted") {
-			t.Fatal("did not receive expected certificate verification failure error")
-		}
+		assert.ErrorIs(t, err, common.TokenVerificationErr)
 	})
 
 	t.Run("OIDC provider is external, TLS is configured, OIDCTLSInsecureSkipVerify is true", func(t *testing.T) {
@@ -703,4 +697,295 @@ requestedScopes: ["oidc"]`, oidcTestServer.URL),
 		assert.NotContains(t, err.Error(), "certificate is not trusted")
 		assert.NotContains(t, err.Error(), "certificate signed by unknown authority")
 	})
+
+	t.Run("OIDC provider is external, audience is not specified", func(t *testing.T) {
+		config := map[string]string{
+			"url": "",
+			"oidc.config": fmt.Sprintf(`
+name: Test
+issuer: %s
+clientID: xxx
+clientSecret: yyy
+requestedScopes: ["oidc"]`, oidcTestServer.URL),
+			"oidc.tls.insecure.skip.verify": "true", // This isn't what we're testing.
+		}
+
+		// This is not actually used in the test. The test only calls the OIDC test server. But a valid cert/key pair
+		// must be set to test VerifyToken's behavior when Argo CD is configured with TLS enabled.
+		secretConfig := map[string][]byte{
+			"tls.crt": utiltest.Cert,
+			"tls.key": utiltest.PrivateKey,
+		}
+
+		settingsMgr := settings.NewSettingsManager(context.Background(), getKubeClientWithConfig(config, secretConfig), "argocd")
+		mgr := NewSessionManager(settingsMgr, getProjLister(), "", NewUserStateStorage(nil))
+		mgr.verificationDelayNoiseEnabled = false
+
+		claims := jwt.RegisteredClaims{Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))}
+		claims.Issuer = oidcTestServer.URL
+		token := jwt.NewWithClaims(jwt.SigningMethodRS256, claims)
+		key, err := jwt.ParseRSAPrivateKeyFromPEM(utiltest.PrivateKey)
+		require.NoError(t, err)
+		tokenString, err := token.SignedString(key)
+		require.NoError(t, err)
+
+		_, _, err = mgr.VerifyToken(tokenString)
+		require.NoError(t, err)
+	})
+
+	t.Run("OIDC provider is external, audience is not specified but is required", func(t *testing.T) {
+		config := map[string]string{
+			"url": "",
+			"oidc.config": fmt.Sprintf(`
+name: Test
+issuer: %s
+clientID: xxx
+clientSecret: yyy
+requestedScopes: ["oidc"]
+skipAudienceCheckWhenTokenHasNoAudience: false`, oidcTestServer.URL),
+			"oidc.tls.insecure.skip.verify": "true", // This isn't what we're testing.
+		}
+
+		// This is not actually used in the test. The test only calls the OIDC test server. But a valid cert/key pair
+		// must be set to test VerifyToken's behavior when Argo CD is configured with TLS enabled.
+		secretConfig := map[string][]byte{
+			"tls.crt": utiltest.Cert,
+			"tls.key": utiltest.PrivateKey,
+		}
+
+		settingsMgr := settings.NewSettingsManager(context.Background(), getKubeClientWithConfig(config, secretConfig), "argocd")
+		mgr := NewSessionManager(settingsMgr, getProjLister(), "", NewUserStateStorage(nil))
+		mgr.verificationDelayNoiseEnabled = false
+
+		claims := jwt.RegisteredClaims{Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))}
+		claims.Issuer = oidcTestServer.URL
+		token := jwt.NewWithClaims(jwt.SigningMethodRS512, claims)
+		key, err := jwt.ParseRSAPrivateKeyFromPEM(utiltest.PrivateKey)
+		require.NoError(t, err)
+		tokenString, err := token.SignedString(key)
+		require.NoError(t, err)
+
+		_, _, err = mgr.VerifyToken(tokenString)
+		require.Error(t, err)
+		assert.ErrorIs(t, err, common.TokenVerificationErr)
+	})
+
+	t.Run("OIDC provider is external, audience is client ID, no allowed list specified", func(t *testing.T) {
+		config := map[string]string{
+			"url": "",
+			"oidc.config": fmt.Sprintf(`
+name: Test
+issuer: %s
+clientID: xxx
+clientSecret: yyy
+requestedScopes: ["oidc"]`, oidcTestServer.URL),
+			"oidc.tls.insecure.skip.verify": "true", // This isn't what we're testing.
+		}
+
+		// This is not actually used in the test. The test only calls the OIDC test server. But a valid cert/key pair
+		// must be set to test VerifyToken's behavior when Argo CD is configured with TLS enabled.
+		secretConfig := map[string][]byte{
+			"tls.crt": utiltest.Cert,
+			"tls.key": utiltest.PrivateKey,
+		}
+
+		settingsMgr := settings.NewSettingsManager(context.Background(), getKubeClientWithConfig(config, secretConfig), "argocd")
+		mgr := NewSessionManager(settingsMgr, getProjLister(), "", NewUserStateStorage(nil))
+		mgr.verificationDelayNoiseEnabled = false
+
+		claims := jwt.RegisteredClaims{Audience: jwt.ClaimStrings{"xxx"}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))}
+		claims.Issuer = oidcTestServer.URL
+		token := jwt.NewWithClaims(jwt.SigningMethodRS256, claims)
+		key, err := jwt.ParseRSAPrivateKeyFromPEM(utiltest.PrivateKey)
+		require.NoError(t, err)
+		tokenString, err := token.SignedString(key)
+		require.NoError(t, err)
+
+		_, _, err = mgr.VerifyToken(tokenString)
+		require.NoError(t, err)
+	})
+
+	t.Run("OIDC provider is external, audience is in allowed list", func(t *testing.T) {
+		config := map[string]string{
+			"url": "",
+			"oidc.config": fmt.Sprintf(`
+name: Test
+issuer: %s
+clientID: xxx
+clientSecret: yyy
+requestedScopes: ["oidc"]
+allowedAudiences:
+- something`, oidcTestServer.URL),
+			"oidc.tls.insecure.skip.verify": "true", // This isn't what we're testing.
+		}
+
+		// This is not actually used in the test. The test only calls the OIDC test server. But a valid cert/key pair
+		// must be set to test VerifyToken's behavior when Argo CD is configured with TLS enabled.
+		secretConfig := map[string][]byte{
+			"tls.crt": utiltest.Cert,
+			"tls.key": utiltest.PrivateKey,
+		}
+
+		settingsMgr := settings.NewSettingsManager(context.Background(), getKubeClientWithConfig(config, secretConfig), "argocd")
+		mgr := NewSessionManager(settingsMgr, getProjLister(), "", NewUserStateStorage(nil))
+		mgr.verificationDelayNoiseEnabled = false
+
+		claims := jwt.RegisteredClaims{Audience: jwt.ClaimStrings{"something"}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))}
+		claims.Issuer = oidcTestServer.URL
+		token := jwt.NewWithClaims(jwt.SigningMethodRS256, claims)
+		key, err := jwt.ParseRSAPrivateKeyFromPEM(utiltest.PrivateKey)
+		require.NoError(t, err)
+		tokenString, err := token.SignedString(key)
+		require.NoError(t, err)
+
+		_, _, err = mgr.VerifyToken(tokenString)
+		assert.NoError(t, err)
+	})
+
+	t.Run("OIDC provider is external, audience is not in allowed list", func(t *testing.T) {
+		config := map[string]string{
+			"url": "",
+			"oidc.config": fmt.Sprintf(`
+name: Test
+issuer: %s
+clientID: xxx
+clientSecret: yyy
+requestedScopes: ["oidc"]
+allowedAudiences:
+- something-else`, oidcTestServer.URL),
+			"oidc.tls.insecure.skip.verify": "true", // This isn't what we're testing.
+		}
+
+		// This is not actually used in the test. The test only calls the OIDC test server. But a valid cert/key pair
+		// must be set to test VerifyToken's behavior when Argo CD is configured with TLS enabled.
+		secretConfig := map[string][]byte{
+			"tls.crt": utiltest.Cert,
+			"tls.key": utiltest.PrivateKey,
+		}
+
+		settingsMgr := settings.NewSettingsManager(context.Background(), getKubeClientWithConfig(config, secretConfig), "argocd")
+		mgr := NewSessionManager(settingsMgr, getProjLister(), "", NewUserStateStorage(nil))
+		mgr.verificationDelayNoiseEnabled = false
+
+		claims := jwt.RegisteredClaims{Audience: jwt.ClaimStrings{"something"}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))}
+		claims.Issuer = oidcTestServer.URL
+		token := jwt.NewWithClaims(jwt.SigningMethodRS256, claims)
+		key, err := jwt.ParseRSAPrivateKeyFromPEM(utiltest.PrivateKey)
+		require.NoError(t, err)
+		tokenString, err := token.SignedString(key)
+		require.NoError(t, err)
+
+		_, _, err = mgr.VerifyToken(tokenString)
+		require.Error(t, err)
+		assert.ErrorIs(t, err, common.TokenVerificationErr)
+	})
+
+	t.Run("OIDC provider is external, audience is not client ID, and there is no allow list", func(t *testing.T) {
+		config := map[string]string{
+			"url": "",
+			"oidc.config": fmt.Sprintf(`
+name: Test
+issuer: %s
+clientID: xxx
+clientSecret: yyy
+requestedScopes: ["oidc"]`, oidcTestServer.URL),
+			"oidc.tls.insecure.skip.verify": "true", // This isn't what we're testing.
+		}
+
+		// This is not actually used in the test. The test only calls the OIDC test server. But a valid cert/key pair
+		// must be set to test VerifyToken's behavior when Argo CD is configured with TLS enabled.
+		secretConfig := map[string][]byte{
+			"tls.crt": utiltest.Cert,
+			"tls.key": utiltest.PrivateKey,
+		}
+
+		settingsMgr := settings.NewSettingsManager(context.Background(), getKubeClientWithConfig(config, secretConfig), "argocd")
+		mgr := NewSessionManager(settingsMgr, getProjLister(), "", NewUserStateStorage(nil))
+		mgr.verificationDelayNoiseEnabled = false
+
+		claims := jwt.RegisteredClaims{Audience: jwt.ClaimStrings{"something"}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))}
+		claims.Issuer = oidcTestServer.URL
+		token := jwt.NewWithClaims(jwt.SigningMethodRS256, claims)
+		key, err := jwt.ParseRSAPrivateKeyFromPEM(utiltest.PrivateKey)
+		require.NoError(t, err)
+		tokenString, err := token.SignedString(key)
+		require.NoError(t, err)
+
+		_, _, err = mgr.VerifyToken(tokenString)
+		require.Error(t, err)
+		assert.ErrorIs(t, err, common.TokenVerificationErr)
+	})
+
+	t.Run("OIDC provider is external, audience is specified, but allow list is empty", func(t *testing.T) {
+		config := map[string]string{
+			"url": "",
+			"oidc.config": fmt.Sprintf(`
+name: Test
+issuer: %s
+clientID: xxx
+clientSecret: yyy
+requestedScopes: ["oidc"]
+allowedAudiences: []`, oidcTestServer.URL),
+			"oidc.tls.insecure.skip.verify": "true", // This isn't what we're testing.
+		}
+
+		// This is not actually used in the test. The test only calls the OIDC test server. But a valid cert/key pair
+		// must be set to test VerifyToken's behavior when Argo CD is configured with TLS enabled.
+		secretConfig := map[string][]byte{
+			"tls.crt": utiltest.Cert,
+			"tls.key": utiltest.PrivateKey,
+		}
+
+		settingsMgr := settings.NewSettingsManager(context.Background(), getKubeClientWithConfig(config, secretConfig), "argocd")
+		mgr := NewSessionManager(settingsMgr, getProjLister(), "", NewUserStateStorage(nil))
+		mgr.verificationDelayNoiseEnabled = false
+
+		claims := jwt.RegisteredClaims{Audience: jwt.ClaimStrings{"something"}, Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))}
+		claims.Issuer = oidcTestServer.URL
+		token := jwt.NewWithClaims(jwt.SigningMethodRS256, claims)
+		key, err := jwt.ParseRSAPrivateKeyFromPEM(utiltest.PrivateKey)
+		require.NoError(t, err)
+		tokenString, err := token.SignedString(key)
+		require.NoError(t, err)
+
+		_, _, err = mgr.VerifyToken(tokenString)
+		require.Error(t, err)
+		assert.ErrorIs(t, err, common.TokenVerificationErr)
+	})
+
+	t.Run("OIDC provider is external, audience is not specified, token is signed with the wrong key", func(t *testing.T) {
+		config := map[string]string{
+			"url": "",
+			"oidc.config": fmt.Sprintf(`
+name: Test
+issuer: %s
+clientID: xxx
+clientSecret: yyy
+requestedScopes: ["oidc"]`, oidcTestServer.URL),
+			"oidc.tls.insecure.skip.verify": "true", // This isn't what we're testing.
+		}
+
+		// This is not actually used in the test. The test only calls the OIDC test server. But a valid cert/key pair
+		// must be set to test VerifyToken's behavior when Argo CD is configured with TLS enabled.
+		secretConfig := map[string][]byte{
+			"tls.crt": utiltest.Cert,
+			"tls.key": utiltest.PrivateKey,
+		}
+
+		settingsMgr := settings.NewSettingsManager(context.Background(), getKubeClientWithConfig(config, secretConfig), "argocd")
+		mgr := NewSessionManager(settingsMgr, getProjLister(), "", NewUserStateStorage(nil))
+		mgr.verificationDelayNoiseEnabled = false
+
+		claims := jwt.RegisteredClaims{Subject: "admin", ExpiresAt: jwt.NewNumericDate(time.Now().Add(time.Hour * 24))}
+		claims.Issuer = oidcTestServer.URL
+		token := jwt.NewWithClaims(jwt.SigningMethodRS256, claims)
+		key, err := jwt.ParseRSAPrivateKeyFromPEM(utiltest.PrivateKey2)
+		require.NoError(t, err)
+		tokenString, err := token.SignedString(key)
+		require.NoError(t, err)
+
+		_, _, err = mgr.VerifyToken(tokenString)
+		require.Error(t, err)
+		assert.ErrorIs(t, err, common.TokenVerificationErr)
+	})
 }

util/settings/settings.go

@@ -118,6 +118,33 @@ type Help struct {
 	BinaryURLs map[string]string `json:"binaryUrl,omitempty"`
 }
 
+// oidcConfig is the same as the public OIDCConfig, except the public one excludes the AllowedAudiences and the
+// SkipAudienceCheckWhenTokenHasNoAudience fields.
+// AllowedAudiences should be accessed via ArgoCDSettings.OAuth2AllowedAudiences.
+// SkipAudienceCheckWhenTokenHasNoAudience should be accessed via ArgoCDSettings.SkipAudienceCheckWhenTokenHasNoAudience.
+type oidcConfig struct {
+	OIDCConfig
+	AllowedAudiences                        []string `json:"allowedAudiences,omitempty"`
+	SkipAudienceCheckWhenTokenHasNoAudience *bool    `json:"skipAudienceCheckWhenTokenHasNoAudience,omitempty"`
+}
+
+func (o *oidcConfig) toExported() *OIDCConfig {
+	if o == nil {
+		return nil
+	}
+	return &OIDCConfig{
+		Name:                   o.Name,
+		Issuer:                 o.Issuer,
+		ClientID:               o.ClientID,
+		ClientSecret:           o.ClientSecret,
+		CLIClientID:            o.CLIClientID,
+		RequestedScopes:        o.RequestedScopes,
+		RequestedIDTokenClaims: o.RequestedIDTokenClaims,
+		LogoutURL:              o.LogoutURL,
+		RootCA:                 o.RootCA,
+	}
+}
+
 type OIDCConfig struct {
 	Name                   string                 `json:"name,omitempty"`
 	Issuer                 string                 `json:"issuer,omitempty"`
@@ -1550,24 +1577,37 @@ func UnmarshalDexConfig(config string) (map[string]interface{}, error) {
 	return dexCfg, err
 }
 
-func (a *ArgoCDSettings) OIDCConfig() *OIDCConfig {
+func (a *ArgoCDSettings) oidcConfig() *oidcConfig {
 	if a.OIDCConfigRAW == "" {
 		return nil
 	}
-	oidcConfig, err := UnmarshalOIDCConfig(a.OIDCConfigRAW)
+	config, err := unmarshalOIDCConfig(a.OIDCConfigRAW)
 	if err != nil {
 		log.Warnf("invalid oidc config: %v", err)
 		return nil
 	}
-	oidcConfig.ClientSecret = ReplaceStringSecret(oidcConfig.ClientSecret, a.Secrets)
-	oidcConfig.ClientID = ReplaceStringSecret(oidcConfig.ClientID, a.Secrets)
-	return &oidcConfig
+	config.ClientSecret = ReplaceStringSecret(config.ClientSecret, a.Secrets)
+	config.ClientID = ReplaceStringSecret(config.ClientID, a.Secrets)
+	return &config
 }
 
-func UnmarshalOIDCConfig(config string) (OIDCConfig, error) {
-	var oidcConfig OIDCConfig
-	err := yaml.Unmarshal([]byte(config), &oidcConfig)
-	return oidcConfig, err
+func (a *ArgoCDSettings) OIDCConfig() *OIDCConfig {
+	config := a.oidcConfig()
+	if config == nil {
+		return nil
+	}
+	return config.toExported()
+}
+
+func unmarshalOIDCConfig(configStr string) (oidcConfig, error) {
+	var config oidcConfig
+	err := yaml.Unmarshal([]byte(configStr), &config)
+	return config, err
+}
+
+func ValidateOIDCConfig(configStr string) error {
+	_, err := unmarshalOIDCConfig(configStr)
+	return err
 }
 
 // TLSConfig returns a tls.Config with the configured certificates
@@ -1606,6 +1646,33 @@ func (a *ArgoCDSettings) OAuth2ClientID() string {
 	return ""
 }
 
+// OAuth2AllowedAudiences returns a list of audiences that are allowed for the OAuth2 client. If the user has not
+// explicitly configured the list of audiences (or has configured an empty list), then the OAuth2 client ID is returned
+// as the only allowed audience. When using the bundled Dex, that client ID is always "argo-cd".
+func (a *ArgoCDSettings) OAuth2AllowedAudiences() []string {
+	if config := a.oidcConfig(); config != nil {
+		if len(config.AllowedAudiences) == 0 {
+			return []string{config.ClientID}
+		}
+		return config.AllowedAudiences
+	}
+	if a.DexConfig != "" {
+		return []string{common.ArgoCDClientAppID}
+	}
+	return nil
+}
+
+func (a *ArgoCDSettings) SkipAudienceCheckWhenTokenHasNoAudience() bool {
+	if config := a.oidcConfig(); config != nil {
+		if config.SkipAudienceCheckWhenTokenHasNoAudience != nil {
+			return *config.SkipAudienceCheckWhenTokenHasNoAudience
+		}
+		return true
+	}
+	// When using the bundled Dex, the audience check is required. Dex will always send JWTs with an audience.
+	return false
+}
+
 func (a *ArgoCDSettings) OAuth2ClientSecret() string {
 	if oidcConfig := a.OIDCConfig(); oidcConfig != nil {
 		return oidcConfig.ClientSecret

util/test/testutil.go

@@ -1,18 +1,22 @@
 package test
 
 import (
+	"encoding/json"
 	"fmt"
 	"io"
 	"net/http"
 	"net/http/httptest"
 	"testing"
 
+	"github.com/golang-jwt/jwt/v4"
 	"github.com/stretchr/testify/require"
+	"gopkg.in/square/go-jose.v2"
 )
 
 // Cert is a certificate for tests. It was generated like this:
-// 		opts := tls.CertOptions{Hosts: []string{"localhost"}, Organization: "Acme"}
-//		certBytes, privKey, err := tls.generatePEM(opts)
+//
+//	opts := tls.CertOptions{Hosts: []string{"localhost"}, Organization: "Acme"}
+//	certBytes, privKey, err := tls.generatePEM(opts)
 var Cert = []byte(`-----BEGIN CERTIFICATE-----
 MIIC8zCCAdugAwIBAgIQCSoocl6e/FR4mQy1wX6NbjANBgkqhkiG9w0BAQsFADAP
 MQ0wCwYDVQQKEwRBY21lMB4XDTIyMDYyMjE3Mjk1MloXDTIzMDYyMjE3Mjk1Mlow
@@ -61,6 +65,48 @@ SDpz4h+Bov5qTKkzcxuu1QWtA4M0K8Iy6IYLwb83DZEm1OsAf4i0pODz21PY/I+O
 VHzjB10oYgaInHZgMUdyb6F571UdiYSB6a/IlZ3ngj5touy3VIM=
 -----END RSA PRIVATE KEY-----`)
 
+// PrivateKey2 is a second RSA key used only for tests. You can use it to see if signing a JWT with a different key
+// fails validation (as it should).
+var PrivateKey2 = []byte(`-----BEGIN RSA PRIVATE KEY-----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+-----END RSA PRIVATE KEY-----`)
+
 func dexMockHandler(t *testing.T, url string) func(http.ResponseWriter, *http.Request) {
 	return func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Content-Type", "application/json")
@@ -123,6 +169,20 @@ func oidcMockHandler(t *testing.T, url string) func(http.ResponseWriter, *http.R
   "claims_supported": ["sub", "aud", "exp"]
 }`, url))
 			require.NoError(t, err)
+		case "/keys":
+			pubKey, err := jwt.ParseRSAPublicKeyFromPEM(Cert)
+			require.NoError(t, err)
+			jwks := jose.JSONWebKeySet{
+				Keys: []jose.JSONWebKey{
+					{
+						Key: pubKey,
+					},
+				},
+			}
+			out, err := json.Marshal(jwks)
+			require.NoError(t, err)
+			_, err = io.WriteString(w, string(out))
+			require.NoError(t, err)
 		default:
 			w.WriteHeader(404)
 		}
@@ -137,4 +197,4 @@ func GetOIDCTestServer(t *testing.T) *httptest.Server {
 		oidcMockHandler(t, ts.URL)(w, r)
 	})
 	return ts
-}
+}