This advisory covers security fixes in Red Hat build of Keycloak 26.2.15 images used on OpenShift Container Platform. The vulnerabilities addressed include CVE-2026-3872 (redirect_uri validation bypass causing information disclosure), CVE-2026-4325 (replay of action tokens due to improper handling of single-use entries), CVE-2026-4636 (UMA policy bypass allowing unauthorized access to victim-owned resources), CVE-2026-4282 (privilege escalation via forged authorization codes due to SingleUseObjectProvider isolation flaw), and CVE-2026-4634 (denial of service via excessive processing of OpenID Connect scope parameters). Red Hat provides updated container images to remediate these issues for on-premise or private cloud deployments.

The vulnerabilities could lead to information disclosure, unauthorized access to resources, privilege escalation, replay attacks, and denial of service conditions within environments using affected versions of Red Hat build of Keycloak. These impacts affect authentication and authorization processes critical to secure identity management in OpenShift deployments.

Red Hat has released updated container images for Red Hat build of Keycloak 26.2.15 that address these vulnerabilities. Users should back up existing installations and apply the updated images as provided by Red Hat. No additional mitigation steps are indicated beyond applying the official update.