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Fencer Intel
high 7.5

CVE-2026-4891 json

CVE-2026-4891

published 6mo ago modified 2mo ago also EUVD-2026-29153

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
6.4%
EPSS 6.4% chance of exploitation in 30 days, percentile 93%
public exploits
0
none known

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.

Patch / fix

  • dnsmasq dnsmasq 2.92rel2
  • Red Hat Red Hat Enterprise Linux 10 0:2.90-7.el10_2
  • Red Hat Red Hat Enterprise Linux 8 0:2.79-36.el8_10
  • Red Hat Red Hat Enterprise Linux 9 0:2.85-18.el9_8.1
  • Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support 0:2.85-17.el9_6.1
  • Red Hat Red Hat OpenShift Container Platform 4.19 4.19.9.6.202607151909-0
  • dnsmasq Debian 12 2.90-4~deb12u2
  • dnsmasq Debian 13 2.91-1+deb13u1
  • dnsmasq Debian 14 2.92-5

debian advisories DEBIAN-CVE-2026-4891

  • dnsmasq Ubuntu 22.04 LTS 2.90-0ubuntu0.22.04.3
  • dnsmasq Ubuntu 24.04 LTS 2.90-2ubuntu0.3
  • dnsmasq Ubuntu 25.10 2.91-1ubuntu0.2
  • dnsmasq Ubuntu 26.04 LTS 2.92-1ubuntu0.2
  • dnsmasq Ubuntu Pro 16.04 LTS 2.90-0ubuntu0.16.04.1+esm3
  • dnsmasq Ubuntu Pro 18.04 LTS 2.90-0ubuntu0.18.04.1+esm3
  • dnsmasq Ubuntu Pro 20.04 LTS 2.90-0ubuntu0.20.04.1+esm2

ubuntu advisories UBUNTU-CVE-2026-4891

Ubuntu security data © Canonical Ltd., from https://github.com/canonical/ubuntu-security-notices via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • dnsmasq RHEL 8 2.79-36.el8_10
  • dnsmasq-utils RHEL 8 2.79-36.el8_10
  • dnsmasq RHEL 9 2.85-18.el9_8.1
  • dnsmasq-utils RHEL 9 2.85-18.el9_8.1
  • dnsmasq RHEL 10.2 2.90-7.el10_2
  • dnsmasq-utils RHEL 10.2 2.90-7.el10_2
  • dnsmasq RHEL 9.6 EUS 2.85-17.el9_6.1
  • dnsmasq-utils RHEL 9.6 EUS 2.85-17.el9_6.1

red hat advisories RHSA-2026:34508RHSA-2026:20589RHSA-2026:19373RHSA-2026:19158

  • dnsmasq SLES LTSS Extended Security 12 SP5, SLES 12 SP5-LTSS 2.92rel2-18.27.1

suse advisories SUSE-SU-2026:2458-1

  • dnsmasq openSUSE Tumbleweed 2.92rel2-1.1

opensuse advisories openSUSE-SU-2026:10821-1

  • dnsmasq AlmaLinux 8 2.79-36.el8_10
  • dnsmasq-utils AlmaLinux 8 2.79-36.el8_10
  • dnsmasq AlmaLinux 10 2.90-7.el10_2
  • dnsmasq-utils AlmaLinux 10 2.90-7.el10_2
  • dnsmasq AlmaLinux 9 2.85-18.el9_8.1
  • dnsmasq-utils AlmaLinux 9 2.85-18.el9_8.1

almalinux advisories ALSA-2026:20589ALSA-2026:19158ALSA-2026:19373

  • dnsmasq Rocky Linux 10 2.90-7.el10_2
  • dnsmasq Rocky Linux 8 2.79-36.el8_10
  • dnsmasq Rocky Linux 9 2.85-18.el9_8.1

rocky linux advisories RLSA-2026:19158RLSA-2026:20589RLSA-2026:19373

  • dnsmasq Alpine 3.23, Alpine 3.22 2.91-r1
  • dnsmasq Alpine 3.24 2.92_p2-r0

alpine advisories ALPINE-CVE-2026-4891

Alpine secdb © Alpine Linux, from https://secdb.alpinelinux.org via OSV; changed: normalised to fixed package versions per release. CC BY-SA 4.0

  • dnsmasq Azure Linux 3.0 2.92-1

azure linux advisories AZL-86757

Azure Linux vulnerability data, Copyright (c) Microsoft Corporation, from https://github.com/microsoft/AzureLinuxVulnerabilityData via OSV, under the MIT licence; changed: normalised to fixed package versions per release. MIT

Is CVE-2026-4891 in your stack? Fencer shows which of your repositories are affected as soon as an advisory lands, and opens the fix as a pull request.

Check with Fencer

Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

red hat product security vex CVE-2026-4891 updated cvss 7.5

dnsmasq: RRSIG rdlen underflow leading to heap OOB read

  • Red Hat Enterprise Linux 6 dnsmasq, dnsmasq-utils
    affected: no fix planned “Will not fix”
  • Red Hat OpenShift Container Platform 4 openshift/ose-rhel-coreos-8
    affected: no fix available
  • Red Hat Enterprise Linux AppStream (v. 8) dnsmasq 2.79-36.el8_10, dnsmasq-utils 2.79-36.el8_10
    fixed: vendor fix RHSA-2026:20589
  • Red Hat Enterprise Linux AppStream (v. 9) dnsmasq 2.85-18.el9_8.1, dnsmasq-utils 2.85-18.el9_8.1
    fixed: vendor fix RHSA-2026:19373
  • Red Hat Enterprise Linux AppStream (v. 10) dnsmasq 2.90-7.el10_2, dnsmasq-utils 2.90-7.el10_2
    fixed: vendor fix RHSA-2026:19158
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) dnsmasq 2.79-15.el8_4.3
    fixed: vendor fix RHSA-2026:98116
  • Red Hat Enterprise Linux AppStream AUS (v.8.6) dnsmasq 2.79-21.el8_6.6
    fixed: vendor fix RHSA-2026:96241
  • Red Hat Enterprise Linux AppStream E4S (v.8.8) dnsmasq 2.79-26.el8_8.5
    fixed: vendor fix RHSA-2026:96246
show 10 more
  • Red Hat Enterprise Linux AppStream E4S (v.9.2) dnsmasq 2.85-6.el9_2.5
    fixed: vendor fix RHSA-2026:95093
  • Red Hat Enterprise Linux AppStream E4S (v.9.4) dnsmasq 2.85-16.el9_4.1
    fixed: vendor fix RHSA-2026:95088
  • Red Hat Enterprise Linux AppStream EUS (v. 10.0) dnsmasq 2.90-4.el10_0.1
    fixed: vendor fix RHSA-2026:92677
  • Red Hat Enterprise Linux AppStream EUS (v.9.6) dnsmasq 2.85-17.el9_6.1, dnsmasq-utils 2.85-17.el9_6.1
    fixed: vendor fix RHSA-2026:34508
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) dnsmasq 2.79-15.el8_4.3
    fixed: vendor fix RHSA-2026:98116
  • Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) dnsmasq 2.79-21.el8_6.6
    fixed: vendor fix RHSA-2026:96241
  • Red Hat Enterprise Linux AppStream TUS (v.8.8) dnsmasq 2.79-26.el8_8.5
    fixed: vendor fix RHSA-2026:96246
  • Red Hat OpenShift Container Platform 4.19 rhcos 4.19.9.6.202607151909
    fixed: vendor fix RHSA-2026:40762
  • Red Hat Enterprise Linux 7 dnsmasq, dnsmasq-utils
    not affected: vulnerable code not in execute path
  • Red Hat Enterprise Linux AppStream AUS (v.8.4) dnsmasq-utils 2.79-15.el8_4.3 Red Hat Enterprise Linux AppStream AUS (v.8.6) dnsmasq-utils 2.79-21.el8_6.6 Red Hat Enterprise Linux AppStream E4S (v.8.8) dnsmasq-utils 2.79-26.el8_8.5 Red Hat Enterprise Linux AppStream E4S (v.9.2) dnsmasq-utils 2.85-6.el9_2.5 Red Hat Enterprise Linux AppStream E4S (v.9.4) dnsmasq-utils 2.85-16.el9_4.1 Red Hat Enterprise Linux AppStream EUS (v. 10.0) dnsmasq-utils 2.90-4.el10_0.1
    +3 more products
    Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.4) dnsmasq-utils 2.79-15.el8_4.3 Red Hat Enterprise Linux AppStream EUS EXTENSION (v.8.6) dnsmasq-utils 2.79-21.el8_6.6 Red Hat Enterprise Linux AppStream TUS (v.8.8) dnsmasq-utils 2.79-26.el8_8.5
    not affected: vulnerable code not present

Red Hat CSAF VEX © Red Hat, Inc., from https://security.access.redhat.com/data/csaf/v2/vex/; changed: reduced to product statuses and remediations. CC BY 4.0 · csaf

CISA SSVC

Exploitation
none
Automatable
no
Technical impact
partial
Assessed
6mo ago

Exploit prediction

6.41% chance of exploitation in the next 30 days, higher than 93% of all scored CVEs (FIRST EPSS, 2026-11-11).

CVSS scores

assigned by version score vector
CISA ADP 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CNA 3.1 5.3 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Affected products

  • dnsmasq dnsmasq
  • Red Hat Red Hat Enterprise Linux 10
  • Red Hat Red Hat Enterprise Linux 8
  • Red Hat Red Hat Enterprise Linux 9
  • Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support
  • Red Hat Red Hat OpenShift Container Platform 4.19
  • Red Hat Red Hat Enterprise Linux 6
  • Red Hat Red Hat Enterprise Linux 7

Classification

Weakness

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

CPEs and fixed versions use Anchore's correction of NVD's data: Added CPE configurations because not yet analyzed by NVD.