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Ubuntu Dnsmasq Critical Denial Of Service And Info Leak 2026-8542-1

ubuntu
Calendar Grey July 14, 2026
Dist Ubuntu Esm H88
Resolve critical security issues in Dnsmasq for multiple Ubuntu LTS versions to prevent potential information exposure or denial of service.
Several security issues were fixed in Dnsmasq.

Summary

Several security issues were fixed in Dnsmasq.

Software Description:

- dnsmasq: Small caching DNS proxy and DHCP/TFTP server

Details:

Yiwei Hou discovered that Dnsmasq incorrectly handled logging of DS or

DNSKEY. A remote attacker could possibly use this issue to cause a

denial of service. (CVE-2026-12725)

It was discovered that Dnsmasq incorrectly validated the length of

fixed-length DNS record fields when parsing NS section records. A remote

attacker could possibly use this issue to cause Dnsmasq to read out of

bounds, possibly exposing sensitive information. (CVE-2026-12969)

Topics%20covered

Topics Covered

security advisory denial of service critical Ubuntu information exposure dnsmasq

Update Instructions

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

Ubuntu 26.04 LTS
  dnsmasq                         2.92-1ubuntu0.4
  dnsmasq-base                    2.92-1ubuntu0.4
  dnsmasq-base-lua                2.92-1ubuntu0.4
  dnsmasq-utils                   2.92-1ubuntu0.4

Ubuntu 24.04 LTS
  dnsmasq                         2.90-2ubuntu0.4
  dnsmasq-base                    2.90-2ubuntu0.4
  dnsmasq-base-lua                2.90-2ubuntu0.4
  dnsmasq-utils                   2.90-2ubuntu0.4

Ubuntu 22.04 LTS
  dnsmasq                         2.90-0ubuntu0.22.04.4
  dnsmasq-base                    2.90-0ubuntu0.22.04.4
  dnsmasq-base-lua                2.90-0ubuntu0.22.04.4
  dnsmasq-utils                   2.90-0ubuntu0.22.04.4

Ubuntu 20.04 LTS
  dnsmasq                         2.90-0ubuntu0.20.04.1+esm3
                                  Available with Ubuntu Pro
  dnsmasq-base                    2.90-0ubuntu0.20.04.1+esm3
                                  Available with Ubuntu Pro
  dnsmasq-base-lua                2.90-0ubuntu0.20.04.1+esm3
                                  Available with Ubuntu Pro
  dnsmasq-utils                   2.90-0ubuntu0.20.04.1+esm3
                                  Available with Ubuntu Pro

Ubuntu 18.04 LTS
  dnsmasq                         2.90-0ubuntu0.18.04.1+esm4
                                  Available with Ubuntu Pro
  dnsmasq-base                    2.90-0ubuntu0.18.04.1+esm4
                                  Available with Ubuntu Pro
  dnsmasq-base-lua                2.90-0ubuntu0.18.04.1+esm4
                                  Available with Ubuntu Pro
  dnsmasq-utils                   2.90-0ubuntu0.18.04.1+esm4
                                  Available with Ubuntu Pro

Ubuntu 16.04 LTS
  dnsmasq                         2.90-0ubuntu0.16.04.1+esm4
                                  Available with Ubuntu Pro
  dnsmasq-base                    2.90-0ubuntu0.16.04.1+esm4
                                  Available with Ubuntu Pro
  dnsmasq-base-lua                2.90-0ubuntu0.16.04.1+esm4
                                  Available with Ubuntu Pro
  dnsmasq-utils                   2.90-0ubuntu0.16.04.1+esm4
                                  Available with Ubuntu Pro

After a standard system update you need to restart dnsmasq to make
all the necessary changes.

References

https://ubuntu.com/security/notices/USN-8542-1

CVE-2026-12725, CVE-2026-12969

Severity
critical
Lowest
Low
Medium
High
Critical

Ubuntu Security Notice USN-8542-1

Topics%20covered

Topics Covered

security advisory denial of service critical Ubuntu information exposure dnsmasq

Package Information

https://launchpad.net/ubuntu/+source/dnsmasq/2.92-1ubuntu0.4
https://launchpad.net/ubuntu/+source/dnsmasq/2.90-2ubuntu0.4
https://launchpad.net/ubuntu/+source/dnsmasq/2.90-0ubuntu0.22.04.4

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