The Easy Appointments WordPress plugin before 3.12.28 does not correctly validate shortcode input in one of its block-rendering actions, checking only the first tag of the supplied string against an allowlist while rendering the entire string, allowing users with contributor-level access to execute arbitrary registered shortcodes.

The Easy Appointments WordPress plugin through 4.0 does not perform capability checks in several of its appointment-management actions, relying only on a nonce that any authenticated user can obtain, allowing users with contributor-level access to read all customers' appointment details and to create, modify, and delete bookings.