The ff_h264_decode_seq_parameter_set function in h264_ps.c in libavcodec in FFmpeg before 1.1.3 does not validate the relationship between luma depth and chroma depth, which allows remote attackers to cause a denial of service (out-of-bounds array access and application crash) or possibly have unspecified other impact via crafted H.264 data.
http://www.ubuntu.com/usn/USN-1790-1
http://git.videolan.org/?p=ffmpeg.git%3Ba=commit%3Bh=bdeb61ccc67911cfc5e20c7cfb1312d0501ca90a