The MStore API plugin for WordPress is vulnerable to Cross-Site Request Forgery due to missing nonce validation on the mstore_update_new_order_message function. This makes it possible for unauthenticated attackers to update new order message via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.
https://plugins.trac.wordpress.org/browser/mstore-api/trunk/mstore-api.php#L248