The MotoPress Appointment Booking plugin for WordPress is vulnerable to Authorization Bypass Through User-Controlled Key in all versions up to, and including, 2.4.4. This is due to the `POST /motopress/appointment/v1/bookings` REST endpoint being registered with `'permission_callback' => '__return_true'`, allowing unauthenticated access, while the `createBooking` handler in `BookingsRestController.php` accepts an attacker-supplied `payment_details.booking_id` value and loads the referenced booking via `findById()` without verifying that the caller owns or has any rights to that booking. This makes it possible for unauthenticated attackers to overwrite the customer name, email address, phone number, and `customer_id` of any non-confirmed victim booking by submitting a request with no reservation items, causing `BookingService::createBooking()` to load the existing victim booking object and persist it with attacker-controlled customer data. Victim booking IDs can be harvested prior to exploitation without authentication by querying the also-publicly-accessible `GET /motopress/appointment/v1/bookings/reservations` endpoint with a guessable `service_id` and date range, and only bookings whose status is not `STATUS_CONFIRMED` (e.g., pending or auto-draft) are valid targets.