That's not the best HN story title (it currently is "Apple Security Update released with several serious vulns"). From what I can tell, this update doesn't have several (known) vulnerabilities, it fixes them.
That's fair. I've edited the title.
If you have an Apple device, be it running macOS, tvOS, watchOS or iOS, you should go update it, right now.
Details aren't entirely clear, but it doesn't seem impossible that these vulns together chain from browser to kernel.
Unfortunate choice of URL, since this is the generic list of all Apple security advisories.
I wanted to link the the most official source. They're sorted by date, so you can just look at the ones released today.