Userinfo endpoint doesn't accept charset #20671

Closes 20671

services/src/main/java/org/keycloak/protocol/oidc/endpoints/UserInfoEndpoint.java

@@ -142,7 +142,11 @@ public class UserInfoEndpoint {
         authorization(accessToken);
 
         try {
-            if (MediaType.APPLICATION_FORM_URLENCODED.equalsIgnoreCase(headers.getHeaderString(HttpHeaders.CONTENT_TYPE))) {
+            
+            String contentType = headers.getHeaderString(HttpHeaders.CONTENT_TYPE);
+            jakarta.ws.rs.core.MediaType mediaType = jakarta.ws.rs.core.MediaType.valueOf(contentType);
+            
+            if (jakarta.ws.rs.core.MediaType.APPLICATION_FORM_URLENCODED_TYPE.isCompatible(mediaType)) {
                 MultivaluedMap<String, String> formParams = request.getDecodedFormParameters();
                 checkAccessTokenDuplicated(formParams);
                 accessToken = formParams.getFirst(OAuth2Constants.ACCESS_TOKEN);

testsuite/integration-arquillian/tests/base/src/test/java/org/keycloak/testsuite/oidc/UserInfoTest.java

@@ -207,6 +207,28 @@ public class UserInfoTest extends AbstractKeycloakTest {
             client.close();
         }
     }
+    
+    @Test
+    public void testSuccess_postMethod_charset_body() throws Exception {
+        Client client = AdminClientUtil.createResteasyClient();
+
+        try {
+            AccessTokenResponse accessTokenResponse = executeGrantAccessTokenRequest(client);
+
+            Form form = new Form();
+            form.param("access_token", accessTokenResponse.getToken());
+
+            WebTarget userInfoTarget = UserInfoClientUtil.getUserInfoWebTarget(client);
+            Response response = userInfoTarget.request()
+                    .header(HttpHeaders.CONTENT_TYPE, MediaType.APPLICATION_FORM_URLENCODED_TYPE.withCharset("utf-8"))
+                    .post(Entity.form(form));
+
+            testSuccessfulUserInfoResponse(response);
+
+        } finally {
+            client.close();
+        }
+    }
 
 
     // KEYCLOAK-8838