Red Hat group policy evaluation logic of Keycloak: improper authorization

Medium6.5CVE-2026-18203 · Published Jul 31, 2026 · updated Aug 7, 2026

A flaw was found in the group policy evaluation logic of Keycloak, an identity and access management solution. When a group policy is set to extend permissions to child groups, the system incorrectly uses a simple text-based prefix check to verify group membership. This allows a user who belongs to a different group with a similar starting name to bypass security checks and gain unauthorized access to administrative functions or protected resources.