A flaw was found in the Organization identity-first login flow of the Keycloak authentication server. Keycloak is an open-source identity and access management solution used to secure modern applications and services. The issue occurs when an attacker who belongs to multiple organizations initiates a login and then switches to a registration or password reset path. During this process, a flag indicating a successful login is not properly cleared when the user is removed from the session. An attacker can then provide a victim's username, and the system incorrectly treats the stale flag as proof of the victim's identity. This allows the attacker to bypass authentication and gain full access to