A systemd security update has been released for Ubuntu Linux 16.04 ESM.

USN-5013-2: systemd vulnerabilities

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Ubuntu Security Notice USN-5013-2
July 20, 2021

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

- Ubuntu 16.04 ESM

Summary:

Several security issues were fixed in systemd.

Software Description:
- systemd: system and service manager

Details:

USN-5013-1 fixed several vulnerabilities in systemd. This update provides
the corresponding update for Ubuntu 16.04 ESM.

Original advisory details:

It was discovered that systemd incorrectly handled certain mount paths. A
local attacker could possibly use this issue to cause systemd to crash,
resulting in a denial of service. (CVE-2021-33910)

Mitchell Frank discovered that systemd incorrectly handled DHCP FORCERENEW
packets. A remote attacker could possibly use this issue to reconfigure
servers. (CVE-2020-13529)

Update instructions:

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

Ubuntu 16.04 ESM:
systemd 229-4ubuntu21.31+esm1

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

References:
  https://ubuntu.com/security/notices/USN-5013-2
  https://ubuntu.com/security/notices/USN-5013-1
CVE-2020-13529, CVE-2021-33910