A Cron security update has been released for Ubuntu Linux 18.04 LTS.

Ubuntu Security Notice USN-5259-2
May 06, 2022

cron vulnerabilities
==========================================================================

A security issue affects these releases of Ubuntu and its derivatives:

- Ubuntu 18.04 LTS

Summary:

Several security issues were fixed in Cron.

Software Description:
- cron: process scheduling daemon

Details:

USN-5259-1 fixed several vulnerabilities in Cron. This update provides
the corresponding update for Ubuntu 18.04 LTS.

Original advisory details:

It was discovered that the postinst maintainer script in Cron unsafely
handled file permissions during package install or update operations.
An attacker could possibly use this issue to perform a privilege
escalation attack. (CVE-2017-9525)

Florian Weimer discovered that Cron incorrectly handled certain memory
operations during crontab file creation. An attacker could possibly use
this issue to cause a denial of service. (CVE-2019-9704)

It was discovered that Cron incorrectly handled user input during crontab
file creation. An attacker could possibly use this issue to cause a denial
of service. (CVE-2019-9705)

It was discovered that Cron contained a use-after-free vulnerability in
its force_rescan_user function. An attacker could possibly use this issue
to cause a denial of service. (CVE-2019-9706)

Update instructions:

The problem can be corrected by updating your system to the following
package versions:

Ubuntu 18.04 LTS:
cron 3.0pl1-128.1ubuntu1.1

In general, a standard system update will make all the necessary changes.

References:
https://ubuntu.com/security/notices/USN-5259-2
https://ubuntu.com/security/notices/USN-5259-1
CVE-2017-9525, CVE-2019-9704, CVE-2019-9705, CVE-2019-9706

Package Information:
https://launchpad.net/ubuntu/+source/cron/3.0pl1-128.1ubuntu1.1