GHSA-rc52-c4hv-w89p (CVE-2026-68500)

Details

Impact

The shop payment webhook POST /{_locale}/update-payment (route sylius_mollie_shop_payment_webhook) accepts two independent, attacker-controlled parameters: id (the Mollie payment ID, verified against Mollie's API) and orderId (the Sylius order ID, read directly from the database). The handler never verifies that the Mollie payment belongs to the referenced order.

An unauthenticated attacker who holds any valid paid Mollie payment ID, for example from a EUR 1 order they placed themselves, can submit it together with any victim orderId. The victim's order payment is then transitioned to completed (or any other Mollie-derived state) without any funds being transferred for that order. Sylius order IDs are sequential integers, and the endpoint requires no authentication, CSRF token or rate limiting, so the attack scales trivially across all pending orders.

Patches

Fixed in versions 2.2.8, 3.2.4 and 3.3.1. The webhook now binds the payment to the order: it reads the Mollie payment ID stored server-side for that order when the payment was created and compares it to the incoming Mollie payment ID. On mismatch the request is acknowledged with HTTP 200 and no state change is applied. HTTP 200 is intentional, because Mollie retries the webhook on any non-2xx response.

The stored ID lives in one of two places depending on the checkout flow, and the fix reads both of them (mirroring CaptureAction):

payment.getDetails()['payment_mollie_id'] for the standard Shop API and Apple Pay Direct flows, stored in CreatePaymentAction.
order.getMolliePaymentId() for the QR-code flow, which stores the ID on the order itself (QrCodeAction).

Reading only the payment details would reject legitimate QR-code payments, because their payment details carry no payment_mollie_id, so both sources must be consulted.