The Salon Booking System plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 8.4.6. This is due to missing or incorrect nonce validation on the 'save_customer' function. This makes it possible for unauthenticated attackers to change the admin role to customer or change the user meta to arbitrary values via a forged request, granted they can trick a site administrator into performing an action such as clicking on a link.