The Payflex Payment Gateway plugin for WordPress is vulnerable to unauthorized modification of data due to a missing capability check on the payment_callback() function in all versions up to, and including, 2.5.0. This makes it possible for unauthenticated attackers to update the status of orders, which can potentially lead to revenue loss.
https://plugins.trac.wordpress.org/browser/payflex-payment-gateway/trunk/partpay.php#L751