The Matroska format decoder in FFmpeg before 0.8.3 does not properly allocate memory, which allows remote attackers to execute arbitrary code via a crafted file.
http://www.mandriva.com/security/advisories?name=MDVSA-2012:076
http://www.mandriva.com/security/advisories?name=MDVSA-2012:075
http://www.mandriva.com/security/advisories?name=MDVSA-2012:074
http://www.ffmpeg.org/releases/ffmpeg-0.8.4.changelog
http://www.ffmpeg.org/releases/ffmpeg-0.7.5.changelog
http://ubuntu.com/usn/usn-1333-1
http://ubuntu.com/usn/usn-1320-1