source: http://www.securityfocus.com/bid/6894/info

Sage is prone to a cross site scripting vulnerability.

This issue is due to insufficient sanitization of input submitted in URI parameters. As a result, an attacker may create a malicious link to a site hosting Sage, which contains malicious HTML or script code.

When such a link is visited by an unsuspecting user, attacker-supplied script code will be interpreted by their web client. 

http://hostname/?mod=<script>alert(document.cookie)</script>&op=browse