Mozilla Firefox before 3.6.26 and 4.x through 6.0, Thunderbird before 3.1.18 and 5.0 through 6.0, and SeaMonkey before 2.4 do not properly enforce the IPv6 literal address syntax, which allows remote attackers to obtain sensitive information by making XMLHttpRequest calls through a proxy and reading the error messages.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A14814
https://bugzilla.mozilla.org/show_bug.cgi?id=504014
http://www.mozilla.org/security/announce/2012/mfsa2012-02.html
http://www.mandriva.com/security/advisories?name=MDVSA-2012:013
http://www.debian.org/security/2012/dsa-2406
http://www.debian.org/security/2012/dsa-2402
http://www.debian.org/security/2012/dsa-2400
http://lists.opensuse.org/opensuse-security-announce/2012-02/msg00011.html
http://lists.opensuse.org/opensuse-security-announce/2012-02/msg00007.html
http://lists.opensuse.org/opensuse-security-announce/2012-02/msg00003.html