pam or ldap storing sessions with old passwords?

[Frank Nørvig]

Hi,

We're having a bit of a problem here at work and I can't seem to find a 
solution.

Problem is:
Whenever a user changes password in our ldap he/she is able to login 
with both the old and the new password on some servers, even though 
theres is only one user entry in ldap.

It seems PAM or maybe LDAP stores a session with the old authentication 
so for a unknown amount of time (at least a week or till server reboot) 
the user can login with the old password.

We have a lot of servers and it only seem to be a problem on RedHat 
Fedora 4. I can't reproduce the problem on RH Fedora 8.

The RH4 PAM system-auth looks like this:
auth        required      pam_env.so
auth        sufficient    pam_unix.so nullok try_first_pass nodelay
auth        requisite     pam_succeed_if.so uid >= 500 quiet
auth        sufficient    pam_ldap.so use_first_pass debug
auth        required      pam_deny.so

account     required      pam_unix.so broken_shadow
account     sufficient    pam_localuser.so
account     sufficient    pam_succeed_if.so uid < 500 quiet
account     [default=bad success=ok user_unknown=ignore] pam_ldap.so
account     required      pam_permit.so

password    requisite     pam_cracklib.so try_first_pass retry=3
password    sufficient    pam_unix.so md5 shadow nullok try_first_pass 
use_authtok
password    sufficient    pam_ldap.so use_authtok
password    required      pam_deny.so

#session     optional      pam_keyinit.so revoke
session     required      pam_limits.so
session     [success=1 default=ignore] pam_succeed_if.so service in 
crond quiet use_uid
session     required      pam_unix.so
session     optional      pam_ldap.so

Is there anyone who got any idea on why this is happening? It's quite 
the security problem :(

Thanks
--- Frank Nørvig
http://www.noervig.dk