CVE-2026-16093

Summary

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.

Affected Software

VendorProductVersion RangeStatus
Red HatRed Hat build of Keycloak 26.626.6.7-3 < *unaffected
Red HatRed Hat build of Keycloak 26.626.6-20 < *unaffected
Red HatRed Hat build of Keycloak 26.626.6-20 < *unaffected

Weaknesses

  • CWE-807: Reliance on Untrusted Inputs in a Security Decision

ADP Enrichment

CISA ADP Vulnrichment

  • SSVC:
  • Exploitation: none
    • Automatable: no
    • Technical Impact: partial

References