CVE-2026-18203

Description

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.

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Produits concernés

• Red Hat Build of Keycloak
• Red Hat Data Grid 8
• Red Hat JBoss Enterprise Application Platform Expansion Pack
• Red Hat Single Sign-On 7
• Redhat build of keycloak

Scores CVSS

Faiblesses (CWE)

• CWE-863

Références

• https://access.redhat.com/security/cve/CVE-2026-18203 Vendor Advisory
• https://bugzilla.redhat.com/show_bug.cgi?id=2508291 Issue TrackingVendor Advisory

Ailleurs

• NVD
• CVE.org
• CIRCL Vulnerability-Lookup
• CERT-FR
• GitHub Advisories