In GetSimpleCMS 3.3.15, admin/upload.php blocks .html uploads but there are several alternative cases in which HTML can be executed, such as a file with no extension or an unrecognized extension (e.g., the test or test.asdf filename), because of admin/upload-uploadify.php, and validate_safe_file in admin/inc/security_functions.php.

In GetSimpleCMS 3.3.15, admin/upload.php blocks .html uploads but Internet Explorer render HTML elements in a .eml file, because of admin/upload-uploadify.php, and validate_safe_file in admin/inc/security_functions.php.

An issue was discovered in GetSimple CMS 3.3.15. An administrator can insert stored XSS via the admin/settings.php Custom Permalink Structure parameter, which injects the XSS payload into any page created at the admin/pages.php URI.

An issue was discovered in GetSimple CMS v3.3.13. There is a CSRF vulnerability that can change the administrator's password via admin/settings.php. NOTE: The vendor reported that the PoC was sending a value for the nonce parameter

There is XSS in GetSimple CMS 3.4.0.9 via the admin/edit.php title field.

GetSimple CMS 3.3.14 has XSS via the admin/edit.php "Add New Page" field.

Cross-site scripting (XSS) vulnerability in admin/template/js/uploadify/uploadify.swf in GetSimple CMS 3.3.13 allows remote attackers to inject arbitrary web script or HTML, as demonstrated by the movieName parameter.

admin/profile.php in GetSimple CMS 3.x has XSS in a name field.

Poor cryptographic salt initialization in admin/inc/template_functions.php in GetSimple CMS 3.3.13 allows a network attacker to escalate privileges to an arbitrary user or conduct CSRF attacks via calculation of a session cookie or CSRF nonce.

GetSimple CMS 3.3.4 allows remote attackers to obtain sensitive information via a direct request to (1) data/users/<username>.xml, (2) backups/users/<username>.xml.bak, (3) data/other/authorization.xml, or (4) data/other/appid.xml.