The vmd_decode function in libavcodec/vmdvideo.c in FFmpeg before 2.5.2 does not validate the relationship between a certain length value and the frame width, which allows remote attackers to cause a denial of service (out-of-bounds array access) or possibly have unspecified other impact via crafted Sierra VMD video data.
The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.