The certificate-warning functionality in browser/components/certerror/content/aboutCertError.xhtml in Mozilla Firefox 4.x through 12.0, Firefox ESR 10.x before 10.0.6, Thunderbird 5.0 through 12.0, Thunderbird ESR 10.x before 10.0.6, and SeaMonkey before 2.10 does not properly handle attempted clickjacking of the about:certerror page, which allows man-in-the-middle attackers to trick users into adding an unintended exception via an IFRAME element.
https://oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A16783
https://bugzilla.mozilla.org/show_bug.cgi?id=633691
http://www.ubuntu.com/usn/USN-1509-2
http://www.ubuntu.com/usn/USN-1509-1
http://www.securityfocus.com/bid/54581
http://www.mozilla.org/security/announce/2012/mfsa2012-54.html
http://secunia.com/advisories/49994
http://secunia.com/advisories/49993
http://secunia.com/advisories/49992
http://secunia.com/advisories/49979
http://secunia.com/advisories/49977
http://secunia.com/advisories/49972
http://secunia.com/advisories/49965
http://rhn.redhat.com/errata/RHSA-2012-1088.html
http://lists.opensuse.org/opensuse-security-announce/2012-07/msg00013.html
http://lists.opensuse.org/opensuse-security-announce/2012-07/msg00012.html
http://lists.opensuse.org/opensuse-security-announce/2012-07/msg00011.html