The Sylius Mollie Plugin integrates Mollie payment services into Sylius applications. Before versions 2.2.8, 3.2.4, and 3.3.1, the payment webhook endpoint (POST /{_locale}/update-payment) accepts parameters 'id' and 'orderId' from the user but fails to verify that the Mollie payment ID corresponds to the Sylius order ID. This lack of verification constitutes an authorization bypass (CWE-639), allowing an unauthenticated attacker who knows any valid paid Mollie payment ID to mark arbitrary orders as paid without actual payment. The vulnerability has a CVSS 3.1 base score of 7.5 (high severity) with network attack vector, low attack complexity, no privileges required, no user interaction, unchanged scope, no confidentiality impact, high integrity impact, and no availability impact. The vulnerability is fixed in Sylius Mollie Plugin versions 2.2.8, 3.2.4, and 3.3.1.

An unauthenticated attacker can mark victim orders as paid without transferring funds by exploiting the lack of verification between Mollie payment IDs and Sylius order IDs. This results in integrity compromise of order payment status, potentially allowing fraudulent order fulfillment without actual payment. There is no confidentiality or availability impact reported.

Upgrade Sylius Mollie Plugin to version 2.2.8, 3.2.4, or 3.3.1 or later, where this authorization bypass vulnerability is fixed. Patch status is confirmed by the vendor's versioning information. No other mitigations are indicated.