Mozilla Firefox before 18.0, Firefox ESR 10.x before 10.0.12 and 17.x before 17.0.2, Thunderbird before 17.0.2, Thunderbird ESR 10.x before 10.0.12 and 17.x before 17.0.2, and SeaMonkey before 2.15 allow remote attackers to spoof the address bar via vectors involving authentication information in the userinfo field of a URL, in conjunction with a 204 (aka No Content) HTTP status code.
http://lists.opensuse.org/opensuse-security-announce/2013-01/msg00006.html
http://lists.opensuse.org/opensuse-security-announce/2013-01/msg00007.html
http://lists.opensuse.org/opensuse-security-announce/2013-01/msg00010.html
http://lists.opensuse.org/opensuse-security-announce/2013-01/msg00017.html
http://rhn.redhat.com/errata/RHSA-2013-0144.html
http://rhn.redhat.com/errata/RHSA-2013-0145.html
https://bugzilla.mozilla.org/show_bug.cgi?id=802026
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A16827
http://www.mozilla.org/security/announce/2013/mfsa2013-04.html
http://www.ubuntu.com/usn/USN-1681-1