XSS in GOT.MY CLASSMATES

Product: CLASSMATES
Vendor: http://www.got.my ( http://www.got.my/CLASSMATES/ )
Vulnerable Version: 1.1.1
Vulnerability Type: XSS (Cross Site Scripting)
Risk level: Medium
Credit: Hector.x90

Vulnerability Details:
User can execute arbitrary JavaScript code within the vulnerable application.
The vulnerability exists due to failure in the "/themes/default/header.inc.php" script to properly sanitize
user-supplied input in "theme_dir" variable then register_globals on.
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.

The following PoC is available:

http://[host]/themes/default/header.inc.php?theme_dir=%22%3E%3Cscript%3E
alert%28document.cookie%29;%3C/script%3E