https://wccftech.com/macos-high-sierra-bug-allows-you-to-unlock-mac-app-store-system-preferences-using-any-password/

Another password related bug has surfaced in macOS, but this one lives inside the System Preferences for the Mac App Store.

Here’s a cool, yet alarming, party trick you can pull off right now. Head over to System Preferences on your Mac, then click on the App Store. Once here, click on the ‘padlock’ icon to unlock it. When prompted, enter your username and any password at all. Then click on Unlock.