Here's hoping that "impossible" isn't the final answer.  Maybe crond can work
around this?

+++ This bug was initially created as a clone of Bug #433788 +++

Description of problem:

crond stopped working after a pam upgrade.  The syslog was littered with crond
PAM errors trying to load pam_access.so and failing.

Version-Release number of selected component (if applicable):
pam-0.99.8.1-17.fc8
vixie-cron-4.2-8.fc8

How reproducible:
happened on several servers

Steps to Reproduce:
1. update to pam-0.99.8.1-17.fc8
2. notice that cron stops running cron jobs
3. note log entries
4. "service crond restart" fixes it

Actual results:

Feb 19 06:40:01 host1 crond[1718]: PAM unable to dlopen(/lib/security/pam_access.so)
Feb 19 06:40:01 host1 crond[1718]: PAM [error: /lib/libpam.so.0: version
`LIBPAM_MODUTIL_1.1' not found (required by /lib/security/pam_access.so)]
Feb 19 06:40:01 host1 crond[1718]: PAM adding faulty module:
/lib/security/pam_access.so

...

Feb 21 08:00:01 host1 crond[14795]: PAM unable to
dlopen(/lib/security/pam_access.so)
Feb 21 08:00:01 host1 crond[14795]: PAM [error: /lib/libpam.so.0: version
`LIBPAM_MODUTIL_1.1' not found (required by /lib/security/pam_access.so)]
Feb 21 08:00:01 host1 crond[14795]: PAM adding faulty module:
/lib/security/pam_access.so

Expected results:

cron should run properly after a pam upgrade.

Additional info:

Problem started immediately after this entry in /var/log/yum.log:

Feb 19 06:36:55 Updated: pam - 0.99.8.1-17.fc8.i386

-- Additional comment from orchard.edu on 2008-02-21 11:02 EST --
I have seen the same thing.  Here is cron.log where it started.  yum was run as
part of cron.daily.

Feb 20 04:02:01 3439-3 CROND[5464]: (root) CMD (run-parts /etc/cron.daily)
Feb 20 04:44:16 3439-3 anacron[5682]: Updated timestamp for job `cron.daily' to
2008-02-20
Feb 20 05:01:01 3439-3 crond[6501]: CRON (root): failed to open PAM security
session: Module is unkn
own
Feb 20 06:01:01 3439-3 crond[6793]: CRON (root): failed to open PAM security
session: Module is unkn
own


-- Additional comment from tmraz on 2008-02-21 12:07 EST --
That's unfortunately impossible to fix.

*** This bug has been marked as a duplicate of 433544 ***