The CleanChanges extension for MediaWiki before 1.19.9, 1.20.x before 1.20.8, and 1.21.x before 1.21.3, when "Group changes by page in recent changes and watchlist" is enabled, allows remote attackers to obtain sensitive information (revision-deleted IPs) via the Recent Changes page.
https://bugzilla.wikimedia.org/show_bug.cgi?id=54294
http://lists.wikimedia.org/pipermail/mediawiki-announce/2013-November/000135.html
http://lists.fedoraproject.org/pipermail/package-announce/2013-December/123011.html
http://lists.fedoraproject.org/pipermail/package-announce/2013-December/122998.html