The Appointment Booking Calendar — Simply Schedule Appointments Booking Plugin plugin for WordPress is vulnerable to Cross-Site Request Forgery in all versions up to, and including, 1.6.6.20. This is due to missing or incorrect nonce validation on the ssa_factory_reset() function. This makes it possible for unauthenticated attackers to reset the plugins settings via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.