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4.207. vixie-cron

An updated vixie-cron package that fixes one security issue, several bugs, and adds one enhancement is now available for Red Hat Enterprise Linux 5.
The Red Hat Security Response Team has rated this update as having low security impact. A Common Vulnerability Scoring System (CVSS) base score, which gives a detailed severity rating, is available from the CVE link associated with the description below.
The vixie-cron package contains the Vixie version of cron. Cron is a standard UNIX daemon that runs specified programs at scheduled times. The vixie-cron package adds improved security and more powerful configuration options to the standard version of cron.

Security Fix

A race condition was found in the way the crontab program performed file time stamp updates on a temporary file created when editing a user crontab file. A local attacker could use this flaw to change the modification time of arbitrary system files via a symbolic link attack.
Red Hat would like to thank Dan Rosenberg for reporting this issue.

Bug Fixes

Cron jobs of users with home directories mounted on a Lightweight Directory Access Protocol (LDAP) server or Network File System (NFS) were often refused because jobs were marked as orphaned (typically due to a temporary NSS lookup failure, when NIS and LDAP servers were unreachable). With this update, a database of orphans is created, and cron jobs are performed as expected.
Previously, cron did not log any errors if a cron job file located in the /etc/cron.d/ directory contained invalid entries. An upstream patch has been applied to address this problem and invalid entries in the cron job files now produce warning messages.
Previously, the "@reboot" crontab macro incorrectly ran jobs when the crond daemon was restarted. If the user used the macro on multiple machines, all entries with the "@reboot" option were executed every time the crond daemon was restarted. With this update, jobs are executed only when the machine is rebooted.
The crontab utility is now compiled as a position-independent executable (PIE), which enhances the security of the system.
When the parent crond daemon was stopped, but a child crond daemon was running (executing a program), the "service crond status" command incorrectly reported that crond was running. The source code has been modified, and the "service crond status" command now correctly reports that crond is stopped.
According to the pam(8) manual page, the cron daemon, crond, supports access control with PAM (Pluggable Authentication Module). However, the PAM configuration file for crond did not export environment variables correctly and, consequently, setting PAM variables via cron did not work. This update includes a corrected /etc/pam.d/crond file that exports environment variables correctly. Setting pam variables via cron now works as documented in the pam(8) manual page.
Previously, the mcstransd daemon modified labels for the crond daemon. When the crond daemon attempted to use the modified label and mcstransd was not running, crond used an incorrect label. Consequently, Security-Enhanced Linux (SELinux) denials filled up the cron log, no jobs were executed, and crond had to be restarted. With this update, both mcstransd and crond use raw SELinux labels, which prevents the problem.
BZ#699620, BZ#699621
Previously, the crontab(1) and cron(8) manual pages contained multiple typographical errors. This update fixes those errors.


Previously, the crontab utility did not use the Pluggable Authentication Module (PAM) for verification of users. As a consequence, a user could access crontab even if access had been restricted (usually by being denied in the access.conf file). With this update, crontab returns an error message that the user is not allowed to access crontab because of PAM configuration.
All vixie-cron users should upgrade to this updated package, which resolves these issues and adds this enhancement.