The vmd_decode function in libavcodec/vmdvideo.c in FFmpeg before 2.5.2 does not validate the relationship between a certain length value and the frame width, which allows remote attackers to cause a denial of service (out-of-bounds array access) or possibly have unspecified other impact via crafted Sierra VMD video data.
https://security.gentoo.org/glsa/201603-06
http://git.videolan.org/?p=ffmpeg.git%3Ba=commit%3Bh=3030fb7e0d41836f8add6399e9a7c7b740b48bfd