Cross-site scripting (XSS) vulnerability in modules/mod_languages/tmpl/default.php in the Language Switcher module for Joomla! 2.5.x before 2.5.7 allows remote attackers to inject arbitrary web script or HTML via the PATH_INFO to index.php. NOTE: some of these details are obtained from third party information.
http://www.openwall.com/lists/oss-security/2012/10/19/4
http://www.openwall.com/lists/oss-security/2012/10/07/3
http://www.joomla.org/announcements/release-news/5463-joomla-2-5-7-released.html
http://secunia.com/advisories/49678
http://developer.joomla.org/security/news/540-20120902-core-xss-vulnerability