How to deal with cross domain problems?

I have some files that are stored under a different ip address. For example: Right now, I am using KmlDataSource.load to load the kml files and add them to the Cesium map. However, my map was loaded from another ip address, say Http:// When I was trying to load the kml files. The browser reported me with an error saying:
XMLHttpRequest cannot load No 'Access-Control-Allow-Origin' header is present on the requested resource. Origin '' is therefore not allowed access.
i {statusCode: undefined, response: undefined, responseHeaders: undefined}

I have totally no idea how to deal with this cross domain issue. I researched on the internet and found someone said that it could be solved by setting up something on the server side, which I think is where the kml files are, am I right? But this is not for me, I don't have the right to work on the server side. Is there any other methods in Cesium I can refer to? Thanks a lot.