The Robokassa payment gateway for Woocommerce WordPress plugin before 1.8.9 does not verify the authenticity of incoming payment notifications when its non-default deferred-payment feature is enabled…

Summary

The Robokassa payment gateway for Woocommerce WordPress plugin before 1.8.9 does not verify the authenticity of incoming payment notifications when its non-default deferred-payment feature is enabled, allowing unauthenticated attackers to forge a notification and mark arbitrary WooCommerce orders as paid or on-hold without payment or a valid signature.