The Public Key Pinning (PKP) implementation in Mozilla Firefox before 33.0 does not properly consider the connection-coalescing behavior of SPDY and HTTP/2 in the case of a shared IP address, which allows man-in-the-middle attackers to bypass an intended pinning configuration and spoof a web site by providing a valid certificate from an arbitrary recognized Certification Authority.
https://security.gentoo.org/glsa/201504-01
https://bugzilla.mozilla.org/show_bug.cgi?id=1049095
http://www.ubuntu.com/usn/USN-2372-1
http://www.securitytracker.com/id/1031028
http://www.securityfocus.com/bid/70432
http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html
http://www.mozilla.org/security/announce/2014/mfsa2014-80.html
http://secunia.com/advisories/62023
http://secunia.com/advisories/62022
http://lists.opensuse.org/opensuse-updates/2014-11/msg00002.html
http://lists.opensuse.org/opensuse-updates/2014-11/msg00001.html
http://lists.fedoraproject.org/pipermail/package-announce/2014-October/141085.html
http://lists.fedoraproject.org/pipermail/package-announce/2014-November/141796.html