[Bug] Proxy does not forward credentials correctly for multi-staged authentication

[michaeljmarshall]

Search before asking

• I searched in the issues and found nothing similar.

Version

Master (and presumably all others)

Minimal reproduce step

Bug discovered while reviewing the code. Inspect the lifecycle of the clientAuthData variable. The variable is set to the last authData received by the client, which means that for multi-staged authentication, it is not possible to forward the authentication credentials.

What did you expect to see?

I'd expect the protocol to either support forwarding these credentials or to fail when configured to do something it is unable to do correctly.

What did you see instead?

Described above.

Anything else?

For added context, I discussed this issue here: #18130 (comment).

Are you willing to submit a PR?

• I'm willing to submit a PR!

[github-actions]

The issue had no activity for 30 days, mark with Stale label.