[kilburn]

If you want an arbitrary (thus https based) website to be able to communicate with a localhost server using websockets you are forced to use https on the localhost server. This is because the browser won't connect to non-secure websockets from an https website, even if the websocket is to localhost.

The actual right thing to do is to generate a private key and certificate (for a specific, public name you point to 127.0.0.1) during the software installation and add the latter to the trusted store. Now you don't have this vulnerability because each computer has a different trusted certificate with a different key, so a random attacker cannot just use the key they got to spy on other users.