The ff_h264_decode_seq_parameter_set function in h264_ps.c in libavcodec in FFmpeg before 0.9.1 and in Libav 0.5.x before 0.5.9, 0.6.x before 0.6.6, 0.7.x before 0.7.6, and 0.8.x before 0.8.3 allows remote attackers to cause a denial of service (application crash) and possibly execute arbitrary code via a crafted H.264 file, related to the chroma_format_idc value.
https://exchange.xforce.ibmcloud.com/vulnerabilities/78933
http://www.ubuntu.com/usn/USN-1479-1
http://www.openwall.com/lists/oss-security/2012/02/14/4
http://www.mandriva.com/security/advisories?name=MDVSA-2013:079
http://www.debian.org/security/2012/dsa-2494
http://git.videolan.org/?p=ffmpeg.git%3Ba=commit%3Bh=7fff64e00d886fde11d61958888c82b461cf99b9