Bugzilla 3.5.x and 3.6.x before 3.6.9, 3.7.x and 4.0.x before 4.0.6, and 4.1.x and 4.2.x before 4.2.1, when the inbound_proxies option is enabled, does not properly validate the X-Forwarded-For HTTP header, which allows remote attackers to bypass the lockout policy via a series of authentication requests with (1) different IP address strings in this header or (2) a long string in this header.
https://bugzilla.mozilla.org/show_bug.cgi?id=728639
http://lists.fedoraproject.org/pipermail/package-announce/2012-May/079604.html
http://lists.fedoraproject.org/pipermail/package-announce/2012-May/079481.html
http://lists.fedoraproject.org/pipermail/package-announce/2012-May/079432.html
http://archives.neohapsis.com/archives/bugtraq/2012-04/0135.html