Advisory by Jose Carlos Norte

Wordpress is vulnerable to XSS attacks when custom 404 pages are used by the template.

The problem (sidebar.php):



if wordpress template use custom 404 pages, like:




        


                
Error 404 - Not Found

        



$_SERVER['PHP_SELF']; can contain special characters to break out html and perform XSS attacks, example:

 

if no custom 404 page set by wordpress theme this attacks is not posible.