The decode_mb function in libavcodec/error_resilience.c in FFmpeg before 0.10 allows remote attackers to have an unspecified impact via vectors related to an uninitialized block index, which triggers an out-of-bounds write.
http://www.ffmpeg.org/security.html
http://git.videolan.org/?p=ffmpeg.git%3Ba=commitdiff%3Bh=c77be3a35a0160d6af88056b0899f120f2eef38e