Keycloak SAML Authentication Bypass

Keycloak contains an authentication bypass vulnerability in its SAML broker functionality that allows remote attackers with low-level privileges to complete IdP-initiated broker logins even when the SAML Identity Provider has been administratively disabled. Red Hat Build of Keycloak versions 26.2 and 26.4 are affected, with patches available in versions 26.2-16, 26.2.14-1, 26.4-12, and 26.4.10-1. The CVSS score of 8.1 reflects high confidentiality and integrity impact, though no evidence of active exploitation (KEV) or public proof-of-concept has been reported at this time.

Keycloak's SAML broker endpoint contains a validation flaw that allows attackers with a valid signed SAML assertion to inject encrypted assertions for arbitrary principals when the overall SAML response is unsigned. This leads to authentication bypass and unauthorized access to protected resources. Red Hat build of Keycloak versions 26.2 and 26.4 are affected, with patches available in versions 26.2-16, 26.2.14-1, 26.4-12, and 26.4.10-1. No evidence of active exploitation (not in CISA KEV) has been reported.