Sylius Mollie Plugin provides Mollie payment integration for Sylius applications. Prior to 2.2.8, 3.2.4, and 3.3.1, Sylius Mollie Plugin's POST /{_locale}/update-payment payment webhook accepts attacker-controlled id and orderId parameters but does not verify that the Mollie payment belongs to the referenced Sylius order, allowing an unauthenticated attacker with any valid paid Mollie payment ID to mark a victim order as paid without transferring funds for that order. This issue is fixed in 2.2.8, 3.2.4, and 3.3.1.