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Ubuntu Security Notice USN-6129-2
July 25, 2023

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

- Ubuntu 18.04 LTS (Available with Ubuntu Pro)
- Ubuntu 16.04 LTS (Available with Ubuntu Pro)
- Ubuntu 14.04 LTS (Available with Ubuntu Pro)

Summary:

Avahi could be made to crash if it received specially crafted DBus traffic.

Software Description:
- avahi: IPv4LL network address configuration daemon

Details:

USN-6129-1 fixed a vulnerability in Avahi. This update provides the
corresponding update for Ubuntu 14.04 LTS, Ubuntu 16.04 LTS and Ubuntu 18.04
LTS.

Original advisory details:

It was discovered that Avahi incorrectly handled certain DBus messages. A
local attacker could possibly use this issue to cause Avahi to crash,
resulting in a denial of service.

Update instructions:

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

Ubuntu 18.04 LTS (Available with Ubuntu Pro):
avahi-daemon 0.7-3.1ubuntu1.3+esm1

Ubuntu 16.04 LTS (Available with Ubuntu Pro):
avahi-daemon 0.6.32~rc+dfsg-1ubuntu2.3+esm2

Ubuntu 14.04 LTS (Available with Ubuntu Pro):
avahi-daemon 0.6.31-4ubuntu1.3+esm2

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

References:
https://ubuntu.com/security/notices/USN-6129-2
https://ubuntu.com/security/notices/USN-6129-1
CVE-2023-1981