Major macOS High Sierra Security Flaw Discovered, Here's How to Protect Your Mac
It would appear that there’s a major security vulnerability in the wild affecting Apple’s macOS High Sierra 10.13 operating system, which could put your personal data in danger.
The security flaw was discovered by developer Lemi Orhan Ergin, who publicly posted it on his Twitter account addressed to Apple Support. The issue can allow an attacker with physical access to a Mac running macOS High Sierra to bypass the lock screen and change any settings without needing your username or password.
This is possible only on Macs that have the Guest User account enabled, which is usually activated by default on macOS High Sierra, as well as on machines where the root (system administrator) account hasn’t yet given a password. Affected systems include macOS 10.13.0, 10.13.1, and 10.13.2 beta.