The Service Finder Bookings plugin for WordPress is vulnerable to privilege escalation via authentication bypass in all versions up to, and including, 6.0. This is due to the plugin not properly validating a user's cookie value prior to logging them in through the service_finder_switch_back() function. This makes it possible for unauthenticated attackers to login as any user including admins.
The system's authorization functionality does not prevent one user from gaining access to another user's data or record by modifying the key value identifying the data.