MediaWiki before 1.15.3, and 1.6.x before 1.16.0beta2, does not properly handle a correctly authenticated but unintended login attempt, which makes it easier for remote authenticated users to conduct phishing attacks by arranging for a victim to login to the attacker's account and then execute a crafted user script, related to a "login CSRF" issue.
https://bugzilla.redhat.com/show_bug.cgi?id=580418
http://www.vupen.com/english/advisories/2010/1055
http://www.openwall.com/lists/oss-security/2010/04/08/4
http://www.openwall.com/lists/oss-security/2010/04/07/1
http://www.debian.org/security/2010/dsa-2041
http://svn.wikimedia.org/svnroot/mediawiki/tags/REL1_16_0beta2/phase3/RELEASE-NOTES
http://svn.wikimedia.org/svnroot/mediawiki/tags/REL1_15_3/phase3/RELEASE-NOTES
http://lists.wikimedia.org/pipermail/mediawiki-announce/2010-April/000090.html
http://download.wikimedia.org/mediawiki/1.16/mediawiki-1.16.0beta2.patch.gz
http://download.wikimedia.org/mediawiki/1.15/mediawiki-1.15.3.patch.gz