The HTTP Alternative Services feature in Mozilla Firefox before 37.0.1 allows man-in-the-middle attackers to bypass an intended X.509 certificate-verification step for an SSL server by specifying that server in the uri-host field of an Alt-Svc HTTP/2 response header.
http://lists.opensuse.org/opensuse-security-announce/2015-04/msg00003.html
http://www.mozilla.org/security/announce/2015/mfsa2015-44.html
http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html
http://www.securitytracker.com/id/1032030
http://www.ubuntu.com/usn/USN-2557-1