WP Travel Engine < 6.8.2 - Unauthenticated Payment Bypass via Missing PayPal IPN Receiver and Amount Verification

The WP Travel Engine WordPress plugin before 6.8.2 does not verify that an incoming PayPal payment notification was sent to the site's configured merchant account, nor that the paid amount matches the order total, before marking a booking as paid, allowing unauthenticated attackers to mark bookings as fully paid using a token payment made to an attacker-controlled account.