source: https://www.securityfocus.com/bid/7966/info

Reportedly, Kerio Mailserver is vulnerable to a cross site-scripting attack. The vulnerability is present in the add_acl module of the Kerio Mailserver web mail component.

An attacker may exploit this vulnerability by enticing a victim user to follow a malicious link.

It should be noted that although this vulnerability has been reported to affect Kerio MailServer version 5.6.3, previous versions might also be affected.

http://www.example.com/add_acl?folder=~conde0@localhost/INBOX&add_name=<script>alert(document.cookie);</script>