Integer overflow in the mov_build_index function in libavformat/mov.c in FFmpeg before 2.8.8, 3.0.x before 3.0.3 and 3.1.x before 3.1.1 allows remote attackers to have unspecified impact via vectors involving sample size.
The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.