local unsigned inb(void *desc, unsigned char **buf)
{
    (void)desc;
    load();
    *buf = g.in_next;
    return g.in_left;
}

The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.