CVE-2026-7571

Vendor solution

To mitigate this issue, restrict network access to the Keycloak authentication endpoint to trusted clients and networks. Implement firewall rules to control inbound connections to the Keycloak service ports, thereby reducing the attack surface and limiting who can initiate authentication flows and potentially exploit the implicit flow bypass. If the Keycloak service is reloaded or restarted, ensure these network restrictions remain in effect.

Red Hat statement

This High severity flaw in Keycloak allows a low-privilege user, with knowledge of user credentials and client ID, to bypass the `implicitFlowEnabled=false` setting. By forging client data during a session restart, an attacker can obtain an implicit access token, potentially exposing it in URL query strings if `response_mode=query` is also forged. This bypass undermines a critical security control intended to prevent implicit flow, leading to unauthorized access to sensitive tokens.

Red Hat mitigation

To mitigate this issue, restrict network access to the Keycloak authentication endpoint to trusted clients and networks. Implement firewall rules to control inbound connections to the Keycloak service ports, thereby reducing the attack surface and limiting who can initiate authentication flows and potentially exploit the implicit flow bypass. If the Keycloak service is reloaded or restarted, ensure these network restrictions remain in effect.