As a software developer that operates in the US we’re required by the US Government to comply with US export controls and sanctions. This means we must enforce geo-blocking controls on our software that prohibit downloads in sanctioned countries. Where a user is located within a sanctioned country, we must make sure that our software cannot be updated in that country.
If you are in a sanctioned country and try to download or update CCleaner, you will see a message that states that you CCleaner is not supported in your current location. If you are in a sanctioned country while travelling, you will be able to download or update CCleaner once you enter an unrestricted country.
You can find the full list of Office of Foreign Assets Control (OFAC) sanctions here.