The Payment Gateway for Redsys & WooCommerce Lite plugin for WordPress is vulnerable to Improper Verification of Cryptographic Signature in versions up to, and including, 7.0.0 due to successful_request() handlers calculating a local signature but not validating Ds_Signature from the request before accepting payment status across the Redsys, Bizum, and Google Pay gateway flows. This makes it possible for unauthenticated attackers to forge payment callback data and mark pending orders as paid when they know a valid order key and order amount, potentially allowing checkout completion and product or service fulfillment without a successful payment.