There is no attack surface because the data exchanged before the upgrade is mostly superfluous. I always felt like the refusal in the WG to add a dedicated TLS-

There is no attack surface because the data exchanged before the upgrade is mostly superfluous. I always felt like the refusal in the WG to add a dedicated TLS-only port in the spec was more feeding someone's conception of niceness than anything else. Happy to see it has become de-facto supported by now though. I tried writing a client in the late 2000s with .NET TlsStream and it was not a great experience.