MacOS High Sierra vulnerability was publicly disclosed in an Apple forum weeks ago

While Apple scrambles to issue a software fix for a major macOS High Sierra vulnerability, astute observers are wondering what took the company so long to react — after all, the problem was known about weeks ago.

It seems that on November 13, a commenter on an Apple developer forum disclosed the very vulnerability that today threw the infosec community into a frenzy. Oh, and it was called out 9 days ago on Twitter as well.

And just how bad is this security threat? Well, it's not good. Essentially, it gives anyone with access to an unlocked computer the ability to set themselves as the root user — as well as log back in later to the locked computer at a time of their choosing.

To execute the hack, you only needed to go to System Preferences > Users & Groups, then enter "root" as your user name while leaving the password field blank. Try this a few times until you have access. It's that simple. The exploit was first explained by Apple developer chethan177.

Again, chethan177 posted this on November 13. Apple only issued instructions on how to protect yourself against this on November 28.

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Whether or not anyone tried to responsibly disclose the threat with Apple remains unclear. But the fact that this attack — which in some cases can be performed remotely — was known to some developers weeks before Apple issued a statement about it is sure to turn heads.

Mashable has reached out to Apple for comment and will update the story as soon as we hear back.