wePOS (Point Of Sale for WooCommerce) before 2.0.3 contains a missing authorization vulnerability in the wepos/v1/payment/process REST route that allows authenticated vendor-level users to mark arbitrary orders as paid and completed by supplying another order's ID. Attackers with only the publish_shop_orders capability (such as Dokan vendor staff) can invoke the payment processing endpoint with an order ID they do not own to trigger the order completion lifecycle, including stock reduction and granting of paid-order access, without making any real payment.