CVE-2013-4304
The CentralAuth extension for MediaWiki 1.19.x before 1.19.8, 1.20.x before 1.20.7, and 1.21.x before 1.21.2 caches a valid CentralAuthUser object in the centralauth_User cookie even when a user has not successfully logged in, which allows remote attackers to bypass authentication without a password.
Date published : 2014-01-26
https://bugzilla.wikimedia.org/show_bug.cgi?id=52338
http://lists.wikimedia.org/pipermail/mediawiki-announce/2013-September/000133.html