/dev/urandom is a major liability on any machine with low uptime booted for the first time from a widely-used image (i.e. a VPS), and on embedded systems which

/dev/urandom is a major liability on any machine with low uptime booted for the first time from a widely-used image (i.e. a VPS), and on embedded systems which have few sources of entropy & do not (or cannot) save/restore it across boots. As a result there can be a much higher than pure-random chance of a collision in the "random" portion of a UUID.