libavcodec/utils.c in FFmpeg before 2.4.2 omits a certain codec ID during enforcement of alignment, which allows remote attackers to cause a denial of service (out-of-bounds access) or possibly have unspecified other impact via crafted JV data.

libavcodec/mjpegdec.c in FFmpeg before 2.4.2 considers only dimension differences, and not bits-per-pixel differences, when determining whether an image size has changed, which allows remote attackers to cause a denial of service (out-of-bounds access) or possibly have unspecified other impact via crafted MJPEG data.