REDHAT-BUG-2464145: CSRF

A session fixation vulnerability in Keycloak's login-actions endpoints allows an unauthenticated attacker to pre-create an authentication session, deliver a crafted link to a victim, and claim the resulting required-action form without the victim entering any credentials. A separate endpoint, /login-actions/restart, accepts the session handle with no CSRF token or cookie ownership check, enabling the attacker to reset flow state so that SSO fires silently when the victim clicks the link. The demonstrated impact on the default Keycloak deployment is full takeover of the master-realm admin account.