There is an XSS in the Wordpress default theme. Tested on WordPress version 2.2

Filename functions.php, line 387.
Code:



$_SERVER['REQUEST_URI'] is directly echoed to the user.

This problem can be exploited if the adminstrator is logged in.

Sample exploit URL.
 

There are other XSS vulnerabilities in popular Wordpress themes.
More details on http://www.xssnews.com/