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