CVE 2011-3947
Buffer overflow in mjpegbdec.c in libavcodec in FFmpeg 0.7.x before 0.7.12 and 0.8.x before 0.8.11, and in Libav 0.5.x before 0.5.9, 0.6.x before 0.6.6, 0.7.x before 0.7.5, and 0.8.x before 0.8.1, allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a crafted MJPEG-B file.
See the 
CVE page on Mitre.org
for more details.
