Vulnerability ID: HTB22995
Reference: http://www.htbridge.ch/advisory/xss_in_ajax_chat.html
Product: Ajax Chat
Vendor: php-development.ru
Vulnerable Version: 1
Vendor Notification: 10 May 2011 
Vulnerability Type: XSS (Cross Site Scripting)
Risk level: Medium 
Credit: High-Tech Bridge SA Security Research Lab ( http://www.htbridge.ch/advisory/ ) 

Vulnerability Details:
User can execute arbitrary JavaScript code within the vulnerable application.
The vulnerability exists due to failure in the "/ajax-chat/ajax-chat.php" script to properly sanitize user-supplied input in "chat_path" variable when register_globals is on.
Successful exploitation of this vulnerability could result in a compromise of the application, theft of cookie-based auwhentication credentials, disclosure or modification of sensitive data.
The following PoC is available:

http://[host]/ajax-chat/ajax-chat.php?chat_path=%27%3C/script%3E%3Cscript%3Ealert%28document.cookie%29;%3C/script%3E