Try it on macOS High Sierra 10.13.2, here are the steps:
This error is worse than the previous Mac lock error because no user name is required, because the authentication dialog only asks for a password and the username is usually filled out. If you go somewhere, forget to unlock it for a while.
But when it is locked, everyone can access it
With this vulnerability, anyone can get administrative rights on the Mac, change the settings related to macOS updates, security patches.
Experiment with this error on two completely successful Macs, allowing access to App Store settings in Preferences with any password, including a letter or a number. Even the part of the username you want to enter is okay.
According to the MacRumors, the error no longer works on the macOS High Sierra 10.3.3 Beta, meaning Apple has overcome it. But many people still use macOS 10.13.2, 10.13.1 or even 10.13. And version 10.13.3 is still in Beta and this month will be officially released.
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