GetSimple CMS v3.3.16 was discovered to contain a remote code execution (RCE) vulnerability via the edited_file parameter in admin/theme-edit.php.
https://github.com/GetSimpleCMS/GetSimpleCMS/issues/1352
http://packetstormsecurity.com/files/172553/GetSimple-CMS-3.3.16-Shell-Upload.html