Vulnerability ID: HTB22951
Reference: http://www.htbridge.ch/advisory/xss_in_wp_ajax_recent_posts_wordpress_plugin.html
Product: WP-Ajax-Recent-Posts wordpress plugin
Vendor: QiQiBoY ( http://www.qiqiboy.com/ ) 
Vulnerable Version: 1.0.1
Vendor Notification: 12 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 "function.php" script to properly sanitize user-supplied input in "number" 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]/?action=wpAjaxRecentPosts&number=1%27%29%22%3E%3Cscript%3Ealert%28123%29;%3C/script%3E