Since this top-line detail is not getting mentioned in a lot of the Discourse: the backdoored versions of #xz / #liblzma are 5.6.0 and 5.6.1. If you've got one of those installed look for an update from your platform provider ASAP.
Personally I can confirm that Homebrew will do the correct downgrade for you (to 5.4.6) if you 'brew upgrade'; I don't have any other vulnerable hosts so I don't have details for what other platforms needed / have patches right now.
