1. Ubuntu Security Notices
  2. USN-5259-3

USN-5259-3: Cron regression

Publication date

11 May 2022

Overview

USN-5259-1 and USN-5259-2 introduced a regression in Cron.

Releases

Packages

  • cron - process scheduling daemon

Details

USN-5259-1 and USN-5259-2 fixed vulnerabilities in Cron. Unfortunately
that update was incomplete and could introduce a regression. This update
fixes the problem.

We apologize for the inconvenience.

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. (

USN-5259-1 and USN-5259-2 fixed vulnerabilities in Cron. Unfortunately
that update was incomplete and could introduce a regression. This update
fixes the problem.

We apologize for the inconvenience.

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

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

Learn more about how to get the fixes.

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

Ubuntu Release Package Version
18.04 bionic cron –  3.0pl1-128.1ubuntu1.2
16.04 xenial cron –  3.0pl1-128ubuntu2+esm2  

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References

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