get-simple GetSimple CMS 3.3.15

GetSimple CMS v3.3.15 has Persistent Cross-Site Scripting (XSS) in admin/theme-edit.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.

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.