---
id: CVE-2026-4891
title: >-
  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.
summary: >-
  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.
severity: medium
cvss: 5.3
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N'
cwe:
  - CWE-125
published: '2026-05-11'
updated: '2026-07-02'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-4891'
references:
  - url: 'https://github.com/NixOS/nixpkgs/pull/519082'
    label: cret@cert.org
  - url: 'https://github.com/NixOS/nixpkgs/pull/519093'
    label: cret@cert.org
  - url: 'https://github.com/pi-hole/FTL/releases/tag/v6.6.2'
    label: cret@cert.org
  - url: >-
      https://lists.thekelleys.org.uk/pipermail/dnsmasq-discuss/2026q2/018471.html
    label: cret@cert.org
  - url: 'https://thekelleys.org.uk/dnsmasq/CVE/'
    label: cret@cert.org
  - url: 'https://www.kb.cert.org/vuls/id/471747'
    label: cret@cert.org
  - url: 'https://access.redhat.com/errata/RHSA-2026:19158'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:19373'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:20589'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/errata/RHSA-2026:34508'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://access.redhat.com/security/cve/CVE-2026-4891'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: 'https://bugzilla.redhat.com/show_bug.cgi?id=2458517'
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
  - url: >-
      https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-4891.json
    label: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c
tags:
  - nvd
epss: 0.06411
epssPercentile: 0.93384
ingestedAt: '2026-07-02T13:35:59.397Z'
---

## Overview

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.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.