The Syliud PayPal Plugin is the Sylius Core Team’s plugin for the PayPal Commerce Platform. Prior to 1.6.2, 1.7.2, and 2.0.2, a discovered vulnerability allows users to modify their shopping cart after completing the PayPal Checkout process and payment authorization. If a user initiates a PayPal transaction from a product page or the cart page and then returns to the order summary page, they can still manipulate the cart contents before finalizing the order. As a result, the order amount in Sylius may be higher than the amount actually captured by PayPal, leading to a scenario where merchants deliver products or services without full payment. The issue is fixed in versions: 1.6.2, 1.7.2, 2.0.2 and above.
The web application does not sufficiently verify inputs that are assumed to be immutable but are actually externally controllable, such as hidden form fields.