Multiple cross-site scripting (XSS) vulnerabilities in WordPress before 3.5.1 allow remote attackers to inject arbitrary web script or HTML via vectors involving (1) gallery shortcodes or (2) the content of a post.
https://bugzilla.redhat.com/show_bug.cgi?id=904121
http://wordpress.org/news/2013/01/wordpress-3-5-1/