HTB22947: XSS in Ajax Category Dropdown wordpress plugin

Vulnerability ID: HTB22947
Reference: http://www.htbridge.ch/advisory/xss_in_ajax_category_dropdown_wordpress_plugin.html
Product: Ajax Category Dropdown wordpress plugin
Vendor: http://www.dyasonhat.com/ ( http://www.dyasonhat.com/ )
Vulnerable Version: 0.1.5
Vendor Notification: 07 April 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 "/wp-content/plugins/ajax-category-dropdown/includes/dhat-ajax-cat-dropdown-request.php" script to properly sanitize user-supplied input in "category_id" 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.

The following PoC is available:

http://[host]/wp-content/plugins/ajax-category-dropdown/includes/dhat-ajax-cat-dropdown-request.php?admin&category_id=%22%3E%3Cscript%3Ealert%28document.cookie%29;%3C/script%3E