Earlier this week, security researchers discovered a critical security flaw affecting Apple computers running the latest version of macOS, High Sierra. Apple has released a security fix for this flaw that is available on the App Store. To obtain it, click on ‘Updates’ in the App Store’s toolbar and download any that are available.

More information about this update and the original security flaw are available at: https://krebsonsecurity.com/2017/11/macos-high-sierra-users-change-root-password-now/