The map_meta_cap function in wp-includes/capabilities.php in WordPress 3.4.x before 3.4.2, when the multisite feature is enabled, does not properly assign the unfiltered_html capability, which allows remote authenticated users to bypass intended access restrictions and conduct cross-site scripting (XSS) attacks by leveraging the Administrator or Editor role and composing crafted text.
http://www.openwall.com/lists/oss-security/2012/07/08/1
http://www.openwall.com/lists/oss-security/2012/07/02/1
http://openwall.com/lists/oss-security/2012/09/12/17