Payment Gateway for PayPal on WooCommerce < 9.2.1 - Unauthenticated Payment Bypass via Sandbox IPN Environment Confusion

Description

The plugin does not verify that an incoming payment notification was confirmed in the store's configured payment environment or paid to the store's own merchant account before marking an order complete, allowing unauthenticated users to mark their own orders as paid using a genuine transaction from a payment sandbox they control.