A flaw was found in Keycloak. This access control vulnerability in Keycloak's OpenID Connect (OIDC) token introspection endpoint allows a confidential client to bypass audience restrictions. An attacker-controlled client with valid credentials can retrieve sensitive token claims intended for other resource servers, compromising the confidentiality of lightweight access tokens. This issue can be exploited remotely by any confidential client in the realm with valid credentials.
Mitigation for this issue is either not available or the currently available options do not meet the Red Hat Product Security criteria comprising ease of use and deployment, applicability to widespread installation base, or stability.