Sylius is an Open Source eCommerce Framework on Symfony. An authenticated Insecure Direct Object Reference (IDOR) vulnerability exists in multiple shop LiveComponents due to unvalidated resource IDs accepted via #[LiveArg] parameters. Unlike props, which are protected by LiveComponent's @checksum, args are fully user-controlled - any action that accepts a resource ID via #[LiveArg] and loads it with ->find() without ownership validation is vulnerable. Checkout address FormComponent (addressFieldUpdated action): Accepts an addressId via #[LiveArg] and loads it without verifying ownership, exposing another user's first name, last name, company, phone number, street, city, postcode, and country. Cart WidgetComponent (refreshCart action): Accepts a cartId via #[LiveArg] and loads any order directly from the repository, exposing order total and item count. Cart SummaryComponent (refreshCart action): Accepts a cartId via #[LiveArg] and loads any order directly from the repository, exposing subtotal, discount, shipping cost, taxes (excluded and included), and order total. Since sylius_order contains both active carts (state=cart) and completed orders (state=new/fulfilled) in the same ID space, the cart IDOR exposes data from all orders, not just active carts. The issue is fixed in versions: 2.0.16, 2.1.12, 2.2.3 and above.