From bleepingcomputer.com
Details have been released for an unpatched vulnerability in macOS 10.14.5 (Mojave) and below that allows a hacker to execute arbitrary code without user interaction.
By leveraging the flaw it is possible to bypass Gatekeeper, the built-in defense in macOS that guards the operating system against running untrusted applications. Gatekeeper achieves this by verifying the code signing certificate obtained through Apple’s developer program.