CVE-2026-117691: keycloak-services: keycloak-services: SAML redirect binding signature bypass via percent-encoded parameter names

Severity: Critical

CVSS Score: 9.1

A flaw was found in the SAML HTTP-Redirect binding implementation of Keycloak. The issue occurs because the server processes percent-encoded parameter names (like %53AMLResponse) while the signature verification logic only checks literal parameter names. An attacker can use this discrepancy to provide a crafted, unsigned SAML message that the server processes instead of a legitimately signed one, leading to full account takeover of federated users.