CVE-2026-16093
No fix known EPSS <1%CVSS 5.4
Keycloak provides a mechanism called Client Policies to enforce security requirements on clients, such as requiring them to use signed JWTs for authentication. A flaw was discovered where this enforcement can be bypassed. An attacker with valid client credentials can provide a fake, unsigned assertion header that tricks the system into thinking the policy requirements have been met. This allows the attacker to authenticate using simpler methods like a client secret even when the administrator has mandated more secure, signed assertions.
Products: Red Hat build of Keycloak 26.6, Red Hat build of Keycloak 26.6.7, Red Hat Data Grid 8, Red Hat JBoss Enterprise Application Platform Expansion Pack, Red Hat Single Sign-On 7