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Amazon Linux 2 : dnsmasq (ALAS-2026-4002)

high Nessus Plugin ID 369105

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Synopsis

The remote Amazon Linux 2 host is missing a security update.

Description

The version of dnsmasq installed on the remote host is prior to 2.76-16. It is, therefore, affected by a vulnerability as referenced in the ALAS2-2026-4002 advisory.

 Amazon Linuxvended DNS resolvers shipped with an older DNSSEC root signing key. For hosts configured with DNSSEC validation enabled, this could result in DNS resolution failures, including for names in unsigned zones. This applies where the resolver is still using the trust anchor shipped in the package;
 resolvers that already picked up the new root key via RFC 5011 are unaffected.

 On 11 October 2026 at 14:00 UTC the DNS root zone began signing with KSK-2024 (key tag 38696), replacing KSK-2017 (key tag 20326). The packaged trust anchor files contained only KSK-2017, so an affected resolver cannot validate the root DNSKEY RRset and returns SERVFAIL.

 The updated packages include an updated root signing key.

Tenable has extracted the preceding description block directly from the tested product security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Run 'yum update dnsmasq' or or 'yum update --advisory ALAS2-2026-4002' to update your system.

See Also

https://alas.aws.amazon.com//AL2/ALAS2-2026-4002.html

https://alas.aws.amazon.com/faqs.html

Plugin Details

Severity: High

ID: 369105

File Name: al2_ALAS-2026-4002.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 10/21/2026

Updated: 10/21/2026

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Continuous Assessment, Tenable Cloud Security, Tenable Self-Hosted Container Security, Nessus

Vulnerability Information

CPE: cpe:/o:amazon:linux:2, p-cpe:/a:amazon:linux:dnsmasq-debuginfo, p-cpe:/a:amazon:linux:dnsmasq-utils, p-cpe:/a:amazon:linux:dnsmasq

Required KB Items: Host/local_checks_enabled, Host/AmazonLinux/release, Host/AmazonLinux/rpm-list

Exploit Ease: No known exploits are available

Patch Publication Date: 10/14/2026

Vulnerability Publication Date: 10/14/2026