Improper signature verification in corvusinfo CorvusPay WooCommerce Payment Gateway

Summary

The CorvusPay WooCommerce Payment Gateway plugin for WordPress is vulnerable to Payment Bypass via Improper Verification of Cryptographic Signature in all versions up to, and including, 2.7.4. The `corvuspay_success_handler` function registers the REST endpoint `POST /wp-json/corvuspay/success/` with `'permission_callback' => '__return_true'`, and while it calls `$this->client->validate->signature()` and stores the boolean result in `$res`, the result is never evaluated in a conditional — it is only written to the debug log — causing execution to unconditionally reach `$order->payment_complete()` regardless of whether the cryptographic signature is valid. This makes it possible for unauthenticated attackers to mark any pending WooCommerce order as fully paid by sending a POST request to the success endpoint containing an arbitrary or forged signature value, allowing them to obtain goods or services without payment. Because WooCommerce order IDs are sequential integers, target orders are trivially enumerable via the `order_number` POST parameter, requiring no prior knowledge of the victim order.