Passwords in VNC Personal Edition for Windows

[Garth A. Reid]

I understand that RealVNC doesn't pass the password from the Viewer to the
Server in clear text. But I've had two instances where people I've set up
with RealVNC have had unexpected connections to their machines. If these
unauthorized users didn't pick up the passwords in clear text transmissions,
then how did they manage to connect? It appears that they were able to get
the password.
  
Thanks,
Garth