CVE-2026-18203 Keycloak-services: keycloak-services: group policy extendchildren matches sibling group path prefixes

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 ...

CVE-2026-18203

CVE-2026-18203 describes a flaw in Keycloak’s group policy evaluation logic: when a group policy is configured to extend permissions to child groups, the system uses a simple text-based prefix check to verify membership. This allows a user from a different group with a similar starting name to by...