Froxlor is open source server administration software. Prior to version 2.3.6, `PhpHelper::parseArrayToString()` writes string values into single-quoted PHP string literals without escaping single quotes. When an admin with `change_serversettings` permission adds or updates a MySQL server via the API, the `privileged_user` parameter (which has no input validation) is written unescaped into `lib/userdata.inc.php`. Since this file is `require`d on every request via `Database::getDB()`, an attacker can inject arbitrary PHP code that executes as the web server user on every subsequent page load. Version 2.3.6 contains a patch.