Man, Ars' headline doesn't sugar-coat things:
“Meltdown” and “Spectre”: Every modern processor has unfixable security flaws https://arstechnica.com/gadgets/2018/01/meltdown-and-spectre-every-modern-processor-has-unfixable-security-flaws/
And for completeness here's Google's blog post: https://security.googleblog.com/2018/01/todays-cpu-vulnerability-what-you-need.html (h/t @netshade and others)
curious what happens next
but tbh this birdsite thread may be the clearest not-too-technical explanation of the flaw that I've seen https://twitter.com/FioraAeterna/status/948684092333158400