path_recv(PG_FUNCTION_ARGS)
{
	StringInfo	buf = (StringInfo) PG_GETARG_POINTER(0);
	PATH	   *path;
	int			closed;
	int32		npts;
	int32		i;
	int			size;

	closed = pq_getmsgbyte(buf);
	npts = pq_getmsgint(buf, sizeof(int32));
	if (npts <= 0 || npts >= (int32) ((INT_MAX - offsetof(PATH, p[0])) / sizeof(Point)))
		ereport(ERROR,
				(errcode(ERRCODE_INVALID_BINARY_REPRESENTATION),
			 errmsg("invalid number of points in external \"path\" value")));

	size = offsetof(PATH, p[0]) +sizeof(path->p[0]) * npts;
	path = (PATH *) palloc(size);

	SET_VARSIZE(path, size);
	path->npts = npts;
	path->closed = (closed ? 1 : 0);
	/* prevent instability in unused pad bytes */
	path->dummy = 0;

	for (i = 0; i < npts; i++)
	{
		path->p[i].x = pq_getmsgfloat8(buf);
		path->p[i].y = pq_getmsgfloat8(buf);
	}

	PG_RETURN_PATH_P(path);
}

This weakness involves numeric computation errors, such as integer overflows, underflows, or precision losses, which can lead to miscalculations and exploitable behaviors in software.