USN-5259-3: Cron regression
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Ubuntu Security Notice USN-5259-3
May 11, 2022
cron regression
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A security issue affects these releases of Ubuntu and its derivatives:
- Ubuntu 18.04 LTS
- Ubuntu 16.04 ESM
Summary:
USN-5259-1 and USN-5259-2 introduced a regression in Cron.
Software Description:
- 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. (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 3.0pl1-128.1ubuntu1.2
Ubuntu 16.04 ESM:
cron 3.0pl1-128ubuntu2+esm2
In general, a standard system update will make all the necessary changes.
References:
https://ubuntu.com/security/notices/USN-5259-1
https://ubuntu.com/security/notices/USN-5259-2
https://ubuntu.com/security/notices/USN-5259-3
https://launchpad.net/bugs/1971895
CVE-2017-9525
Package Information:
https://launchpad.net/ubuntu/+source/cron/3.0pl1-128.1ubuntu1.2
A Cron regression update has been released for Ubuntu Linux 16.04 ESM and 18.04 LTS.
