ccsetup570.exe (free version reporting [fixed]

[teleman56]

Windows Defender reports CCleaner as "Potentially unwanted app with latest Free version update ccsetup570.exe

[nukecad]

Yes, Defender/MS Security Centre is now doing that, - It's because of a new setting "Potentially unwanted app blocking", you can turn it off if you want to.

Note that the words used are  POTENTIALLY UNWANTED.

Only you can decide if you want something or not.

But it seems that Microsoft have deemed that you can no longer be trusted make your own decisions about what to download/install and that they have to nanny you.
Who decides if an app is classed as "low-reputation" by Defender/Windows Security is of course Microsoft themselves.
(And at the moment it seems to be that if it's not in the Microsoft Store then they will give it a "low-reputation").

It's like how Google are always trying to push you to their Play Store.

In the case of CCleaner Microsoft say that they are doing it because the Standard CCleaner installer may (it doesn't always) offer you another product, such as AVG antivirus, you can always decline that offer if you don't want AVG or whatever is being offered.

[Dave CCleaner]

This has been confirmed as a false positive and had already sorted itself out Saturday afternoon (along with a Dr Web false positive as well).  As of the time of writing, Windows Defender should now have no problems with the free version of CCleaner 5.70.

We get this from time to time with new releases of CCleaner - an AV company's threat detection robots will observe that something they haven't seen before is suddenly getting millions of downloads in a day and they block it "just in case" until their analysts can take a look at it and mark it as safe.  Some companies are more consistently on the ball than others when it comes to trying to avoid inconvenience to their users.  As a general rule, if your AV is pinging false positives and you would rather not let your shields down then waiting 12-72 hours and trying again will generally do the trick.