source: https://www.securityfocus.com/bid/10251/info

It has been reported that Moodle is susceptible to a cross-site scripting vulnerability in the 'help.php' script. This issue is due to a failure of the application to properly sanitize user-supplied input prior to including it in dynamic web content.

This issue may allow for theft of cookie-based authentication credentials. Other attacks are also possible.

http://www.example.com/help.php?text={XSS}