The other problem is that the High Sierra firmware checker will only check to see if your system matches the signature on the server. And there's no way to check if your system has a specific zero-day vulnerability or not. It would appear it is only the Mac Pro 5.1 machines that are needing the firmware update. We are getting reports (thanks Mick Corey) that when Mac Pro 5.1 owners are installing macOS 10.13 High Sierra that Apple is updating the Firmware as part of the High Sierra install.
Mac Pro Needs A Firmware Update For High Sierra.
