Retrieve AWS App Config Configuration from ReactJS APP

I am trying to use AWS AppConfig Service within my ReactJS App but I am having problem with CORS.

When I try to fetch my configuration with

AppConfig.getConfiguration({
  Application: 'XXXXXXX', /* required */
  ClientId: 'XXXXXXX', /* required */
  Configuration: 'XXXXXXX', /* required */
  Environment: 'XXXXXX', /* required */
  ClientConfigurationVersion: '1'
}, (err, data) => {
  console.log("err = ", err);
  console.log("data = ", data);
})

I am getting: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.

If it matters, I am using Amazon System Manager document as configuration source.

I am guessing there is a CORS policy configuration for AppConfig/System Manager service just like for the S3 and API Gateway services but I can't find it.

Any help appreciated!