The ff_mpv_common_init function in libavcodec/mpegvideo.c in FFmpeg before 2.7.2 does not properly maintain the encoding context, which allows remote attackers to cause a denial of service (invalid pointer access) or possibly have unspecified other impact via crafted MPEG data.
https://lists.debian.org/debian-lts-announce/2018/12/msg00009.html
http://www.securitytracker.com/id/1033483
http://git.videolan.org/?p=ffmpeg.git%3Ba=commit%3Bh=b160fc290cf49b516c5b6ee0730fd9da7fc623b1