Earlier quoted context omitted.
Whether it's the server's or the client's fault doesn't matter that much from a legal perspective. Intent plays a big role: if you knew that ending a URL with "\" causes `rm -rf /*` to be run, and intentionally run that on a server, you could likely be prosecuted and convicted if it were proven that you did it intentionally. If it were done accidentally by a client, they would (likely, and hopefully) not be convicted…
No, Weev did not "exploit" anything. He _requested_ information from a server. If the server owner had so desired, they could have made the data private by adding a password. They chose not to. In the end, the decision to offer Weev the data was made _by the server_ . And if you're going to bring up the UserAgent spoofing, let me remind you that most browsers have done something like that for > 15 years.
> If the server owner had so desired, they could have made the data private by adding a password.
But the server is still just sending data in response to a request, even with a password. The only reason a password is a line we draw is intent. It's hard to say you didn't realise that guessing at someones password was wrong.