source: http://www.securityfocus.com/bid/5829/exploit

Monkey HTTP server is prone to cross site scripting vulnerabilities. 

An attacker may exploit this vulnerability by enticing a victim user to follow a malicious link. Attacker-supplied HTML and script code may be executed on a web client visiting the malicious link in the context of the webserver.

Attackers may potentially exploit this issue to manipulate web content or to steal cookie-based authentication credentials. It may be possible to take arbitrary actions as the victim user.

www.victim.com/<script>alert('test');</script>
www.victim.com/cgi-bin/test2.pl?<script>alert('test');</script>