Amazon Linux 2 : dnsmasq, --advisory ALAS2DNSMASQ-2026-004 (ALASDNSMASQ-2026-004)

high Nessus Plugin ID 316945

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 2.90-1. It is, therefore, affected by multiple vulnerabilities as referenced in the ALAS2DNSMASQ-2026-004 advisory.

A Denial of Service (DoS) vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet. (CVE-2026-4890)

A heap-based out-of-bounds read vulnerability in the DNSSEC validation of dnsmasq allows remote attackers to cause a denial of service via a crafted DNS packet. (CVE-2026-4891)

A heap-based out-of-bounds write vulnerability in the DHCPv6 implementation of dnsmasq allows local attackers to execute arbitrary code with root privileges via a crafted DHCPv6 packet. (CVE-2026-4892)

An information disclosure vulnerability in dnsmasq allows remote attackers to bypass source checks via a crafted DNS packet with RFC 7871 client subnet information. (CVE-2026-4893)

A buffer overflow in dnsmasq's extract_addresses() function allows an attacker to trigger a heap out-of- bounds read and crash by exploiting a malformed DNS response, enabling extract_name() to advance the pointer past the record's end. (CVE-2026-5172)

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

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

Solution

Run 'yum update dnsmasq' or or 'yum update --advisory ALAS2DNSMASQ-2026-004' to update your system.

Plugin Details

Severity: High

ID: 316945

File Name: al2_ALASDNSMASQ-2026-004.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Amazon Linux Local Security Checks

Published: 5/27/2026

Updated: 5/27/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

CVSS v2

Risk Factor: High

Base Score: 8.3

Temporal Score: 6.1

Vector: CVSS2#AV:A/AC:L/Au:N/C:C/I:C/A:C

CVSS Score Source: CVE-2026-4892

CVSS v3

Risk Factor: High

Base Score: 8.4

Temporal Score: 7.3

Vector: CVSS:3.0/AV:L/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

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

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

Exploit Ease: No known exploits are available

Patch Publication Date: 5/26/2026

Vulnerability Publication Date: 5/11/2026

Reference Information

CVE: CVE-2026-4890, CVE-2026-4891, CVE-2026-4892, CVE-2026-4893, CVE-2026-5172

IAVA: 2026-A-0450

Detections

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