GStreamer before 1.4.5, as used in Mozilla Firefox before 38.0, Firefox ESR 31.x before 31.7, and Thunderbird before 31.7 on Linux, allows remote attackers to cause a denial of service (buffer over-read and application crash) or possibly execute arbitrary code via crafted H.264 video data in an m4v file.
https://www.mozilla.org/en-US/security/known-vulnerabilities/thunderbird/#thunderbird31.7
https://security.gentoo.org/glsa/201512-07
https://lists.debian.org/debian-lts-announce/2020/03/msg00038.html
https://bugzilla.mozilla.org/show_bug.cgi?id=1080995
http://www.oracle.com/technetwork/topics/security/bulletinapr2016-2952098.html
http://www.mozilla.org/security/announce/2015/mfsa2015-47.html
http://www.debian.org/security/2015/dsa-3264
http://www.debian.org/security/2015/dsa-3260
http://www.debian.org/security/2015/dsa-3225
http://rhn.redhat.com/errata/RHSA-2015-1012.html
http://rhn.redhat.com/errata/RHSA-2015-0988.html
http://lists.opensuse.org/opensuse-security-announce/2015-06/msg00000.html
http://lists.opensuse.org/opensuse-security-announce/2015-05/msg00017.html