Mozilla Firefox before 36.0 does not properly recognize the equivalence of domain names with and without a trailing . (dot) character, which allows man-in-the-middle attackers to bypass the HPKP and HSTS protection mechanisms by constructing a URL with this character and leveraging access to an X.509 certificate for a domain with this character.
https://security.gentoo.org/glsa/201504-01
https://bugzilla.mozilla.org/show_bug.cgi?id=1065909
http://www.ubuntu.com/usn/USN-2505-1
http://www.securityfocus.com/bid/72752
http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html
http://www.mozilla.org/security/announce/2015/mfsa2015-13.html
http://lists.opensuse.org/opensuse-updates/2015-03/msg00067.html
http://lists.opensuse.org/opensuse-security-announce/2015-03/msg00000.html