The site has been hacked. After you change your password, your new password might be vulnerable to anyone who happens to know the hack that made the current passwords available, so plan on changing it again.
The good news is that if you aren't a janitor and aren't in Saints in our Book your password was *not* disclosed to the general public, as far as anyone here can tell. I would change it anyway, what the heck. See your profile page to change your password.