source: https://www.securityfocus.com/bid/14326/info

A cross-site scripting vulnerability affects Form Sender. This issue is due to a failure of the application to properly sanitize user-supplied URI input that will be output in dynamically generated Web pages.

This may facilitate the theft of cookie-based authentication credentials as well as other attacks.

http://[target]/[path]/processform.php3?failed=<script>alert(document.cookie)</script>