QUOTE(Superlatanium @ Dec 21 2016, 01:03)

I'm only 80% certain about this, but I think that as soon as a user's password gets changed, the forum (and every associated login) would start immediately rejecting the ipb_pass_hash value of any other user that hasn't used the new password to log in. Because the saved password hash in the cookie doesn't match the hash the E-H servers have, it should reject authentication, and make it impossible to post or login to HV or anything, really.
If the members table comes from Invision (as it should be since you are redirected to Invision login if you put a wrong password in hentaiverse.org) it works in a slighly different way.
A members has:
- a password hash
- a salt
- a login key (member_login_key column in the DB)
- a login key expire date (member_login_key_expire column)
When you change a password you can choose to reset the login key or keep the existing one.
If you keep the existing one as long as the cookie is not deleted or the login key expires the user can still automatically login.
This is the reset password form

As long as you put Create New Log In Key to false the user should still be able to login after the password has been changed (the explanation below seems to confirm this).
Not sure it helps but at least it should clear some doubts.