Some Programs Allow Logins with No Password

You probably have the same problem as in ("Some Programs (E.g. xdm)
Won't Allow Logins."), with an added wrinkle.

If you are using shadow passwords, you should put a letter `x' or an
asterisk in the password field of /etc/passwd for each account, so
that if a program doesn't know about the shadow passwords it won't
think it's a passwordless account and let anyone in.
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