Mozilla Firefox before 37.0 does not require an HTTPS session for lightweight theme add-on installations, which allows man-in-the-middle attackers to bypass an intended user-confirmation requirement by deploying a crafted web site and conducting a DNS spoofing attack against a mozilla.org subdomain.
https://security.gentoo.org/glsa/201512-10
https://bugzilla.mozilla.org/show_bug.cgi?id=1128126
http://www.ubuntu.com/usn/USN-2550-1
http://www.securitytracker.com/id/1031996
http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html
http://www.mozilla.org/security/announce/2015/mfsa2015-32.html
http://lists.opensuse.org/opensuse-security-announce/2015-04/msg00003.html