Ubuntu 21.04: USN-5008-1 Critical Denial of Service in Avahi

ubuntu

July 7, 2021

Several security issues were fixed in Avahi.

Summary

Several security issues were fixed in Avahi.

Software Description:

- avahi: IPv4LL network address configuration daemon

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. This issue only affected

Ubuntu 18.04 LTS, Ubuntu 20.04 LTS, and Ubuntu 20.10. (CVE-2021-3468)

It was discovered that Avahi incorrectly handled certain hotnames. A local

attacker could possibly use this issue to cause Avahi to crash, resulting

in a denial of service. This issue only affected Ubuntu 20.10 and Ubuntu

21.04. (CVE-2021-3502)

Topics Covered

security advisory denial of service local attack ubuntu network issues avahi

Update Instructions

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

Ubuntu 21.04:
  avahi-daemon                    0.8-5ubuntu3.1
  libavahi-core7                  0.8-5ubuntu3.1

Ubuntu 20.10:
  avahi-daemon                    0.8-3ubuntu1.1
  libavahi-core7                  0.8-3ubuntu1.1

Ubuntu 20.04 LTS:
  avahi-daemon                    0.7-4ubuntu7.1
  libavahi-core7                  0.7-4ubuntu7.1

Ubuntu 18.04 LTS:
  avahi-daemon                    0.7-3.1ubuntu1.3
  libavahi-core7                  0.7-3.1ubuntu1.3

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