HTB22844: XSS in GD Star Rating wordpress plugin

Vulnerability ID: HTB22844
Reference: http://www.htbridge.ch/advisory/xss_in_gd_star_rating_wordpress_plugin.html
Product: GD Star Rating wordpress plugin
Vendor: Milan Petrovic ( http://www.gdstarrating.com/ )
Vulnerable Version: 1.9.7
Vendor Notification: 08 February 2011
Vulnerability Type: XSS (Cross Site Scripting)
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 "/wp-content/plugins/gd-star-rating/widgets/widget_top.php" script to properly sanitize user-supplied input in "wpfn" variable when register_globals is 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]/wp-content/plugins/gd-star-rating/widgets/widget_top.php?wpfn="><script>alert("XSS");</script>