flicvideo.c in libavcodec 0.6 and earlier in FFmpeg, as used in MPlayer and other products, allows remote attackers to execute arbitrary code via a crafted flic file, related to an "arbitrary offset dereference vulnerability."
The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment.