Emacs 25.3 has been released on Monday. Given that it’s a security fix I’m downloading the source as I write this. If you’re using the latest Emacs I’d recommend you update your Emacs. The vulnerability as been around since Emacs 19.29, you probably want to upgrade anyway.

Build instructions for Ubuntu and friends are the same as before, the FreeBSD port appears to have been updated already and I’m sure homebrew is soon to follow if they haven’t updated it already.