Well, here‘s a fun one. Your BIOS is the small computer built into your main computer that handles things like the boot sequence, and everything else that happens before you’ve loaded your operating system. And in many cases an attacker with access to your machine can write their own code to it simply by having your machine go to sleep and then waking it up again.
This is not a remote exploit, and it’s unlikely to actually affect you unless you’re being explicitly targeted. But you should update your BIOS with a fixed version, if your machine is affected. If you’re on OS X then just keeping up-to-date with your OS updates will do the trick, but on Windows you’ll need to get an update from your computer’s manufacturer, not from Microsoft. So far only some Apple and Dell machines are known to be affected.