libavcodec/mmvideo.c in FFmpeg before 2.4.2 does not consider all lines of HHV Intra blocks during validation of image height, which allows remote attackers to cause a denial of service (out-of-bounds access) or possibly have unspecified other impact via crafted MM video data.
http://git.videolan.org/?p=ffmpeg.git;a=commit;h=8b0e96e1f21b761ca15dbb470cd619a1ebf86c3e
http://www.ffmpeg.org/security.html