Mozilla Firefox before 43.0 mishandles the # (number sign) character in a data: URI, which allows remote attackers to spoof web sites via unspecified vectors.
http://lists.fedoraproject.org/pipermail/package-announce/2015-December/174083.html
http://lists.fedoraproject.org/pipermail/package-announce/2015-December/174253.html
http://lists.opensuse.org/opensuse-updates/2015-12/msg00104.html
http://lists.opensuse.org/opensuse-updates/2016-02/msg00007.html
http://lists.opensuse.org/opensuse-updates/2016-02/msg00008.html
https://bugzilla.mozilla.org/show_bug.cgi?id=1221444
https://security.gentoo.org/glsa/201512-10
http://www.mozilla.org/security/announce/2015/mfsa2015-141.html