CVE-2026-6498: Five Star Restaurant Reservations <= 2.7.16 - Unauthenticated Payment Bypass via PHP Type Juggling in 'payment_id' Parameter

The Five Star Restaurant Reservations plugin for WordPress is vulnerable to a payment bypass via PHP type juggling in versions up to, and including, 2.7.16 This is due to the validpayment() function using a PHP loose comparison (==) between the attacker-controlled paymentid POST parameter and the booking's stripepaymentintentid property. When an unauthenticated attacker submits a request to the nopriv AJAX handler rtbstripepmtsucceed before the Stripe payment intent has been created for a booking (i.e., before the JavaScript-triggered createstripepmtIntnt() call has stored an intent ID in post meta), the stripepaymentintentid property on the booking object remains null. The comparison sanitizetextfield('') == null evaluates to TRUE in PHP loose comparison, causing the payment verification check to pass with zero actual payment. This makes it possible for unauthenticated attackers to mark any existing paymentpending booking as paid without completing a Stripe payment by submitting an empty paymentid parameter.