The Appointment Booking Calendar Plugin and Online Scheduling Plugin – BookingPress plugin for WordPress is vulnerable to authentication bypass in versions 1.1.6 to 1.1.7. This is due to the plugin not properly verifying a user's identity prior to logging them in when completing a booking. This makes it possible for unauthenticated attackers to log in as registered users, including administrators, if they have access to that user's email. This is only exploitable when the 'Auto login user after successful booking' setting is enabled.