vixie cron does not use pam and also does not read /etc/security/limits.conf file. The problem is that if i normally set limits for all users (number of processes, amount of memory, etc) with just editing /etc/pam.d/(ssh,login,you name it) file and setting it to use /etc/security/pam_limits.so, then i cant do this for cron. And users can execute programs by setting cronjobs or at jobs. To those programs the limits do not apply and so can user override limits set by administrator.
*** This bug has been marked as a duplicate of 5160 ***
*** Bug 157290 has been marked as a duplicate of this bug. ***