Alongside macOS High Sierra 10.13.3, released today, Apple has also issued Security Update 2018-001 for macOS Sierra and macOS El Capitan.

This update also fixes other serious security vulnerabilities, including an issue that could cause an application to run arbitrary code using kernel privileges by exploiting a vulnerability on the IOHIDFamily API. It also patches an issue that could lead to arbitrary code execution when playing a malicious sound file.

The security update is included with macOS High Sierra 10.13.3 and it is also available as a separate security update for users of Sierra on 10.12.6 and El Capitan on 10.11.6. Check the Mac App Store for the updates.

Source: 9to5mac