The Salon Booking System WordPress plugin before 10.31.9 does not correctly verify the authenticity of REST API requests and discards WordPress core's nonce check for cookie-authenticated sessions across the whole REST API, allowing unauthenticated attackers who trick a logged-in administrator into clicking a crafted link to forge requests in that administrator's browser, up to creating a new administrator account.
https://wpscan.com/vulnerability/755ad5f7-44bb-45a9-9de2-f280586deaa3/