Comment by eqvinox

Yup, that's the way to explain it in order to blame musl.

Here's how to explain it in order to blame openssh:

openssh processes passwords and doesn't want to reveal through timing whether a user has a valid password (or exists at all). So far so good.

What they do if they hit a user with no valid password (i.e. "*") is that they look for another user with a valid password, to use the seed from. A bit weird already, but OK from a perspective of avoiding implementation specifics on seeds and hash algorithms. They know at this point that the result must be to deny access even if the hashed value matches, because that hash is for another user.

So they put the password received over ssh into crypt() with this other user's hashed value to get a seed. And then accept it if it matches, apparently?

Homework: what happens if the password actually matches another user? Can I log in as root if openssh randomly picks my user for the fake salt, and I type my own password correctly?