A flaw was found in the JWT Authorization Grant implementation of the keycloak-services component. When an OIDC or Google identity provider is configured with specific login restrictions, such as claim filtering, these checks are correctly applied during standard browser logins but are skipped during the JWT-based grant flow. This allows an authenticated client to obtain access tokens for a user even if their identity provider claims should have blocked the login.
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.