systemd vulnerabilities

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

* Ubuntu 19.10
* Ubuntu 18.04 LTS
* Ubuntu 16.04 LTS

Summary

Several security issues were fixed in systemd.

Software Description

* systemd - system and service manager

Details

It was discovered that systemd incorrectly handled certain PIDFile
files. A local attacker could possibly use this issue to trick
systemd into killing privileged processes. This issue only
affected Ubuntu 16.04 LTS. (CVE-2018-16888)

It was discovered that systemd incorrectly handled certain udevadm
trigger commands. A local attacker could possibly use this issue
to cause systemd to consume resources, leading to a denial of
service. (CVE-2019-20386)

Jann Horn discovered that systemd incorrectly handled services
that use the DynamicUser property. A local attacker could possibly
use this issue to access resources owned by a different service in
the future. This issue only affected Ubuntu 18.04 LTS.
(CVE-2019-3843, CVE-2019-3844)

Tavis Ormandy discovered that systemd incorrectly handled certain
Polkit queries. A local attacker could use this issue to cause
systemd to crash, resulting in a denial of service, or possibly
execute arbitrary code and escalate privileges. (CVE-2020-1712)

Update instructions

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

Ubuntu 19.10
systemd - 242-7ubuntu3.6

Ubuntu 18.04 LTS
systemd - 237-3ubuntu10.38

Ubuntu 16.04 LTS
systemd - 229-4ubuntu21.27

To update your system, please follow these instructions:
https://wiki.ubuntu.com/Security/Upgrades.

After a standard system update you need to reboot your computer to
make all the necessary changes.

References

* CVE-2018-16888
* CVE-2019-20386
* CVE-2019-3843
* CVE-2019-3844
* CVE-2020-1712

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