A session invalidation flaw exists in x-ui 0.3.2. The full user object is stored in a client-side signed cookie, and authentication only checks that a user object can be retrieved from the cookie without re-validating against the database or any session version. When an administrator changes the username or password, previously issued session cookies are not revoked, so an attacker who holds a pre-change admin cookie can continue accessing and operating the management interface after the credentials have been rotated.