CVE-2026-16108: Keycloak-services: keycloak-services: realm default-group reads disclose hidden groups under fgap v2
A flaw was found in the default-groups REST endpoint and realm representation of Keycloak. This component is responsible for managing groups that are automatically assigned to new users within a realm. The issue allows a delegated administrator with realm-viewing permissions to see the names and identifiers of hidden default groups, even if they lack the specific permissions to view those groups. This can lead to the exposure of sensitive organizational structures or internal group names.
Other sources
A flaw was found in the Keycloak Admin REST API when Fine-Grained Admin Permissions (FGAP) v2 is enabled. The default-groups endpoint and the general realm representation do not correctly enforce per-group view permission checks for default groups. A delegated administrator who has been granted realm-level view permissions but is explicitly denied view permissions for specific groups can still enumerate those hidden groups. By accessing the admin/realms/{realm}/default-groups or admin/realms/{realm} endpoints, the attacker can recover group names, UUIDs, and paths. This allows an authenticated attacker to map out the authorization topology, including onboarding structures, privilege levels, or tenant information that should remain restricted.
— Red Hat
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-16108?
The severity of CVE-2026-16108 is rated as medium with a score of 4.3.
How do I fix CVE-2026-16108?
To resolve CVE-2026-16108, ensure that proper permissions are configured for delegated administrators in Keycloak.
What software is affected by CVE-2026-16108?
CVE-2026-16108 affects the Keycloak Admin REST API and the default-groups REST endpoint.
What type of vulnerability is CVE-2026-16108?
CVE-2026-16108 is a disclosure vulnerability that allows unauthorized visibility of hidden groups.
Who is impacted by CVE-2026-16108?
Delegated administrators with realm-viewing permissions in Keycloak can be impacted by CVE-2026-16108.