https://github.com/ascendr/spectre-chrome https://github.com/cgvwzq/spectre https://github.com/alephsecurity/spectreBrowserResearch https://react-etc.net/entry/exploiting-speculative-execution... https://www.tomshardware.com/news/meltdown-spectre-exploit-b...

(I haven't found a JS PoC for Meltdown but I didn't look long.)

I opened the first link. The description starts with.

    Enable `#shared-array-buffer` in `chrome:///flags` under your own risk...

Shared Array Buffers are enabled by default in Chrome now, because Chrome has separate mitigations against Spectre.

To the best of my knowledge, it does not have mitigations against Meltdown because it assumes those protections will be implemented at the OS/firmware level, but if anyone has more experience or insight than me on that front, they're welcome to correct me.

In any case, you're making a kind of wild assumption that the type of user who disables a security feature from their OS to get a speed increase won't also likely disable security features like Site Isolation in their browser when they hear that those features increase Chrome's memory usage by somewhere between 10-20%.

Cool. I wasn't aware Chrome re-enabled SABs, with mitigations.

https://github.com/tc39/ecma262/issues/1435

So there's a known exploit in CPUs and your response is "prove to me it can be exploited or I won't use mitigations"? In 2020 no less? What can you possibly be doing that would even notice the slowdown from these mitigations? Virtually everything we actually do will be bottlenecked by something else long before the CPU becomes an issue.