XSS vulnerability in Ecomat CMS

Vulnerability ID: HTB22391
Reference: http://www.htbridge.ch/advisory/xss_vulnerability_in_ecomat_cms.html
Product: Ecomat CMS
Vendor: Codefabrik GmbH
Vulnerable Version: 5.0 and Probably Prior Versions
Vendor Notification: 18 May 2010
Vulnerability Type: XSS (Cross Site Scripting)
Status: Not Fixed, Vendor Alerted, Awaiting Vendor Response
Risk level: Medium
Credit: High-Tech Bridge SA (http://www.htbridge.ch/)

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

The vulnerability exists due to failure in the "index.php" script to properly sanitize user-supplied input in "lang" 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:

http://host/index.php?type=web&lang=xx%22+onmouseover=alert%28123%29+style=position:absolute;left:0;top:0;width:100%;height:100%+&show=25&mhs=0