Unrestricted file upload vulnerability in the chunk upload API in MediaWiki 1.19 through 1.19.6 and 1.20.x before 1.20.6 allows remote attackers to execute arbitrary code by uploading a file with an executable extension.
https://bugzilla.wikimedia.org/show_bug.cgi?id=48306
http://www.openwall.com/lists/oss-security/2013/05/24/3
http://security.gentoo.org/glsa/glsa-201310-21.xml
http://secunia.com/advisories/55433
http://lists.wikimedia.org/pipermail/mediawiki-announce/2013-May/000131.html