Edit: Updating with their release blogpost instead, as it's clearer:

Release Post: http://www.piriform.com/news/release-announcements/2017/9/18...

Affected Versions:

>This compromise only affected customers with the 32-bit version of the v5.33.6162 of CCleaner and the v1.07.3191 of CCleaner Cloud. No other Piriform or CCleaner products were affected. We encourage all users of the 32-bit version of CCleaner v5.33.6162 to download v5.34 here: download. We apologize and are taking extra measures to ensure this does not happen again.

macOS seems fine, it looks like it was their 32bit Windows/Cloud offerings:

http://www.piriform.com/news/blog/2017/9/18/security-notific...

>Before delving into the technical details, let me say that the threat has now been resolved in the sense that the rogue server is down, other potential servers are out of the control of the attacker, and we’re moving all existing CCleaner v5.33.6162 users to the latest version. Users of CCleaner Cloud version 1.07.3191 have received an automatic update. In other words, to the best of our knowledge, we were able to disarm the threat before it was able to do any harm.

So if you have a Windows copy, look for a patch I guess. Seems like it's not just fixed, but the rogue server taken down.