Apple has now fixed the major macOS High Sierra security flaw

A Turkish software developer has publicly revealed via Twitter that he has uncovered a massive security bug in macOS High Sierra, Apple’s latest operating system. 

Update: Apple has now released a fix for this update, so you should implement it immediately. To do this open up the Mac App Store and click on 'Updates'. Select the security update (2017-001) then click 'Update'. You may also want to follow the steps listed below to make sure you have a root account with a password you have set. Apple has also apologised for the security lapse. The apology, something Apple doesn't make a habit of doing, plus the speed of the fix, shows just how serious the security flaw was.

The flaw grants anyone using a Mac machine admin access by just clicking ‘other’ on the login screen and using ‘root’ as the username, no password needed.

In fact, access to the computer can also be achieved using the username ‘root’ via System Preferences where, to change essential settings on locked Mac devices, users would normally need to enter their login details.

This bug seems to present in macOS High Sierra 10.13.1 – the current version – as well as in the macOS 10.13.2 beta, but does not affect older versions of macOS, like Sierra or El Capitan.

This doesn’t bode well for users on the latest release of macOS – leaving a Mac unattended could make anyone system administrator without any authentication, even when accessed remotely, revealing sensitive information.