Several security issues were fixed in systemd.
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)
5 February 2020
A security issue affects these releases of Ubuntu and its derivatives:
Several security issues were fixed in systemd.
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)
The problem can be corrected by updating your system to the following package versions:
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.
Vulmon