There is a discussion over at SP about SERIOUS CRE Loaded Security Issue Revealed which affects 1000s of stores affected. Better hurry and patch yours if yours is among them!
Here is the fix: in the file admin/includes/application_top.php Simply find the line: $PHP_SELF = (isset($_SERVER['PHP_SELF']) ? $_SERVER['PHP_SELF'] : $_SERVER['SCRIPT_NAME']); and replace with: $PHP_SELF = $_SERVER['SCRIPT_NAME'];