A serious bug has been discovered in High Sierra, the most recent version of the Mac operating system. This flaw allows anyone to gain “root” access to a macOS device, which gives the ability to view or modify any settings or files on the device—including those of other users.
Apple has released a security update to fix this bug. Apply any available macOS software updates through the app store as soon as possible. Apple’s release notes for this update include instructions for confirming that it has been installed. If you are unable to install the update for any reason, Apple has also released instructions for a workaround to protect you until you are able to apply the update. Until you either install the security update or implement the workaround, do not leave your Mac unattended.
UPDATE: Some users may experience difficulty sharing files after applying the security update. If you think you might be affected by this new bug, follow these steps:
- Open the Terminal app, which is in the Utilities folder of your Applications folder.
- Type sudo /usr/libexec/configureLocalKDC and press RETURN.
- Enter your administrator password and press RETURN.
- Quit the Terminal app.