The GMAce plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 1.5.2. This is due to missing nonce validation on the gmace_manager_server function called via the wp_ajax_gmace_manager AJAX action. This makes it possible for unauthenticated attackers to modify arbitrary files and achieve remote code execution 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/gmace/trunk/inc/filemanager.php?rev=1583319#L27
https://plugins.trac.wordpress.org/browser/gmace/trunk/gmace.php?rev=1583327#L84