An Avahi security update has been released for Ubuntu Linux 14.04 ESM and 16.04 ESM.

USN-5008-2: Avahi vulnerability

=========================================================================
Ubuntu Security Notice USN-5008-2
July 07, 2021

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

- Ubuntu 16.04 ESM
- Ubuntu 14.04 ESM

Summary:

Avahi could be made to denial of service if it received a specially crafted input.

Software Description:
- avahi: Avahi IPv4LL network address configuration daemon

Details:

USN-5008-1 fixed a vulnerability in avahi. This update provides
the corresponding update for Ubuntu 14.04 ESM and Ubuntu 16.04 ESM.

Original advisory details:

Thomas Kremer discovered that Avahi incorrectly handled termination signals
on the Unix socket. A local attacker could possibly use this issue to cause
Avahi to hang, resulting in a denial of service.

Update instructions:

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

Ubuntu 16.04 ESM:
avahi-daemon 0.6.32~rc+dfsg-1ubuntu2.3+esm1
libavahi-core7 0.6.32~rc+dfsg-1ubuntu2.3+esm1

Ubuntu 14.04 ESM:
avahi-daemon 0.6.31-4ubuntu1.3+esm1
libavahi-core7 0.6.31-4ubuntu1.3+esm1

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

References:
  https://ubuntu.com/security/notices/USN-5008-2
  https://ubuntu.com/security/notices/USN-5008-1
CVE-2021-3468