Like I've said before, if you're on 4.0.0-5.1.0, then you should stay there if you care about a guaranteed way to make homebrew (as the WebKit exploit works and AFAIK the kernel exploit has been tested up as far as 5.0.0). If you're anything above that, you can probably update considering the nature of the kernel exploit, and the fact that they're using such an old version of WebKit so we can find another bug to gain code execution with. HOWEVER, this is not a guarantee. You can either update, or not. It's up to you.