Different from most bugs, these are not software related, but hardware -- in the chips made by Intel and ARM (used on mobile devices). And so they affect Windows, Apple and Android devices alike. Called Meltdown and Spectre, they aren't precisely "bugs," though more a case flaws since it's how the chips are actually designed to work.
(The very short version is that when you initiate a command, the CPU on the chip is accessed, and it makes a guess what you're next-likely command will be that speeds up the process. That micro-second time its waiting makes the data on the chip vulnerable, like passwords, and someone malicious can fool the chip into initiating that delay.)
The good news is that a hacker still has to infect your system with a virus to allow for them to act further, so the more you can do to protect yourself from that initial infection the better. Also, this aspect of chips has been around for over 20 years, and there is no record of anyone because hacked by it -- though now that the information is known, it's more likely. In addition, though, software and hardware makers are already sending out fixes that can be installed.
Microsoft, for instance, has already sent out a patch for Windows. Browsers are particularly vulnerable, and the Chrome browser has a fix in its next update that's coming in weeks. Microsoft and Mozilla browsers will be patched, as well, though no date is set. But all software should be always kept updated. Apple no doubt will be patching its software, as well, but they haven't responded yet to journalists' inquiries. So adorably self-protective of them...
Here are two, very readable articles from C/NET which you might have useful:
This first here is an read an easy-to-read article that describes all this above in far-better detail.
The other article offers some easy heads-up tips on how to protect yourself, which can be read here.