RHEL 8 : dnsmasq (RHSA-2026:20589)

high Nessus Plugin ID 316738

Synopsis

The remote Red Hat host is missing one or more security updates for dnsmasq.

Description

The remote Redhat Enterprise Linux 8 host has packages installed that are affected by multiple vulnerabilities as referenced in the RHSA-2026:20589 advisory.

The dnsmasq packages contain Dnsmasq, a lightweight DNS (Domain Name Server) forwarder and DHCP (Dynamic Host Configuration Protocol) server.

Security Fix(es):

* dnsmasq: dnsmasq: heap buffer overflow in cache via NAME_ESCAPE expansion (CVE-2026-2291)

* dnsmasq: NSEC bitmap parsing infinite loop (CVE-2026-4890)

* dnsmasq: RRSIG rdlen underflow leading to heap OOB read (CVE-2026-4891)

* dnsmasq: DHCPv6 CLID buffer overflow in helper process (CVE-2026-4892)

* dnsmasq: Broken ECS source validation bypass (CVE-2026-4893)

For more details about the security issue(s), including the impact, a CVSS score, acknowledgments, and other related information, refer to the CVE page(s) listed in the References section.

Tenable has extracted the preceding description block directly from the Red Hat Enterprise Linux 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

Update the RHEL dnsmasq package based on the guidance in RHSA-2026:20589.

Plugin Details

Severity: High

ID: 316738

File Name: redhat-RHSA-2026-20589.nasl

Version: 1.1

Type: Local

Agent: unix

Family: Red Hat Local Security Checks

Published: 5/26/2026

Updated: 5/26/2026

Supported Sensors: Frictionless Assessment AWS, Frictionless Assessment Azure, Frictionless Assessment Agent, Nessus Agent, Agentless Assessment, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.7

Vendor

Vendor Severity: Important

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:redhat:enterprise_linux:8, p-cpe:/a:redhat:enterprise_linux:dnsmasq, p-cpe:/a:redhat:enterprise_linux:dnsmasq-utils, cpe:/o:redhat:rhel_eus:8.10

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

Exploit Ease: No known exploits are available

Patch Publication Date: 5/26/2026

Vulnerability Publication Date: 5/11/2026

Reference Information

CVE: CVE-2026-2291, CVE-2026-4890, CVE-2026-4891, CVE-2026-4892, CVE-2026-4893

CWE: 122, 125, 131, 20, 835

RHSA: 2026:20589

Detections

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