[Altern4tiveAcc]

So, if someone hosts an image editor as web app, are they liable if someone uses that editor to create CP?

I honestly don't follow it. People creating nudes of others and using the Internet to distribute it can be sued for defamation, sure. I don't think the people hosting the service should be liable themselves, just like people hosting Tor nodes shouldn't be liable by what users of the Tor Network do.