MP4Box is a component of GPAC-2.0.0, which is a widely-used third-party package on RPM Fusion. When MP4Box tries to parse a MP4 file, it calls the function `diST_box_read()` to read from video. In this function, it allocates a buffer `str` with fixed length. However, content read from `bs` is controllable by user, so is the length, which causes a buffer overflow.