If you have a Mac running macOS High Sierra — the most recent version of macOS — I have good news and bad news.
The bad news is that Apple made a huge mistake, an outrageous and “inexcusable” security gaff. Since the release of High Sierra, a back door has been left wide open.
The good news is that it’s unlikely any bad guys noticed it… and Apple fixed it less than 24 hours after the vulnerability was publicly exposed. (And publicly exposing it was kind of dick move, BTW. Serious zero-day exploits should not be broadcast.)
But this is going to go down in history as one of Apple’s most egregious software quality bloopers. It might just be the worst. bug. ever. Definitely worse than goto fail.