source: https://www.securityfocus.com/bid/7570/info

A cross site scripting vulnerability has been reported for PHP-Nuke. Specifically, PHP-Nuke does not sufficiently sanitize user-supplied input for the 'username' URI parameter to the modules.php script.

This may allow for theft of cookie-based authentication credentials and other attacks. 

http://[victim]/modules.php?name=Your_Account&op=userinfo&
username=bla<script>alert(document.cookie)</script>