able to join private server without a password
It's possible to connect to a private server, without entering the password.
docs/examples/servinit.cfg mentions these two entries:
// serverpass "p4ssw0rd" // server password required to successfully connect, used for private servers, THIS IS NOT THE ADMIN PASSWORD
// adminpass "4dm1np4ss" // server password for administrators (change the password to your own, of course) // to gain access this way, go in game, connect to your server, and use /setmaster 4dm1np4ss
However; When setting this, the server appears as private listed in the server browser, but you can still connect with a blank or incorrect password:
serverpass "p4ssw0rd"
sv_serveropen 0
Are you sure you're not using your authkey to override it?
IIRC, i did try with a fresh home folder where no authkey was set, and it still happened.