Vulnerability-Lookup

CVE-2026-4891 (GCVE-0-2026-4891)

Vulnerability from cvelistv5 – Published: 2026-05-11 16:47 – Updated: 2026-09-01 12:04

Title

CVE-2026-4891

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

5.3 (Medium)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

7.5 (High)


                        
                          CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-05-11 18:27 UTC

CWE

CWE-125 - Out-of-bounds Read

Assigner

certcc CNA under the mitre root

CNA scorecard E 42/100 over 156 records in the last 180 days details

References

14 references

URL	Tags
https://lists.thekelleys.org.uk/pipermail/dnsmasq…
https://www.kb.cert.org/vuls/id/471747
https://thekelleys.org.uk/dnsmasq/CVE/
https://github.com/NixOS/nixpkgs/pull/519082
https://github.com/NixOS/nixpkgs/pull/519093
https://github.com/pi-hole/FTL/releases/tag/v6.6.2
https://access.redhat.com/security/cve/CVE-2026-4891	vdb-entryx_refsource_REDHAT
https://bugzilla.redhat.com/show_bug.cgi?id=2458517	issue-trackingx_refsource_REDHAT
https://security.access.redhat.com/data/csaf/v2/v…	x_sadp-csaf-vex
https://access.redhat.com/errata/RHSA-2026:40762	vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:19158	vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:20589	vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:34508	vendor-advisoryx_refsource_REDHAT
https://access.redhat.com/errata/RHSA-2026:19373	vendor-advisoryx_refsource_REDHAT

Impacted products

8 products

Vendor	Product	Version	CPE status
dnsmasq	dnsmasq	Affected: 0 , < 2.92rel2 (custom)	guessed
Red Hat	Red Hat Enterprise Linux 10	Unaffected: 0:2.90-7.el10_2 , < * (rpm) cpe:/o:redhat:enterprise_linux:10.2
Red Hat	Red Hat Enterprise Linux 8	Unaffected: 0:2.79-36.el8_10 , < * (rpm) cpe:/a:redhat:enterprise_linux:8
Red Hat	Red Hat Enterprise Linux 9	Unaffected: 0:2.85-18.el9_8.1 , < * (rpm) cpe:/a:redhat:enterprise_linux:9
Red Hat	Red Hat Enterprise Linux 9.6 Extended Update Support	Unaffected: 0:2.85-17.el9_6.1 , < * (rpm) cpe:/a:redhat:rhel_eus:9.6
Red Hat	Red Hat OpenShift Container Platform 4.19	Unaffected: 4.19.9.6.202607151909-0 , < * (rpm) cpe:/a:redhat:openshift:4.19::el9
Red Hat	Red Hat Enterprise Linux 6	cpe:/o:redhat:enterprise_linux:6
Red Hat	Red Hat Enterprise Linux 7	cpe:/o:redhat:enterprise_linux:7

Show details on NVD website

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RHSA-2026:40762

Vulnerability from csaf_redhat - Published: 2026-07-22 12:55 - Updated: 2026-10-14 03:18

Summary

Red Hat Security Advisory: OpenShift Container Platform 4.19.39 bug fix and security update

Severity

Important

Scope

10 vulnerabilities in this advisory, including CVE-2026-4891.

CVE-2026-4891

A heap out-of-bounds read vulnerability was discovered in dnsmasq's DNSSEC validation. When processing RRSIG records, dnsmasq calculates the signature length by subtracting the fixed field size from the record's declared data length. A crafted RRSIG record with a data length smaller than the fixed fields causes this calculation to underflow, potentially resulting in an out-of-bounds read and process crash.

7.5 (High)


                
                  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Fixed: 4 products

https://access.redhat.com/errata/RHSA-2026:40762

Open the full advisory

SUSE-SU-2026:1934-1

Vulnerability from csaf_suse - Published: 2026-05-18 07:40 - Updated: 2026-05-18 07:40

Summary

Security update for dnsmasq

Severity

Important

Scope

7 vulnerabilities in this advisory, including CVE-2026-4891.

CVE-2026-4891

5.3 (Medium)


                
                  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Recommended: 40 products

Open the full advisory

SUSE-SU-2026:21640-1

Vulnerability from csaf_suse - Published: 2026-05-13 16:34 - Updated: 2026-10-12 17:24

Summary

Security update for dnsmasq

Severity

Important

Scope

7 vulnerabilities in this advisory, including CVE-2026-4891.

CVE-2026-4891

5.3 (Medium)


                
                  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Recommended: 4 products

Open the full advisory

SUSE-SU-2026:21677-1

Vulnerability from csaf_suse - Published: 2026-05-15 10:44 - Updated: 2026-09-20 18:38

Summary

Security update for dnsmasq

Severity

Important

Scope

7 vulnerabilities in this advisory, including CVE-2026-4891.

CVE-2026-4891

5.3 (Medium)


                
                  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Recommended: 3 products

Open the full advisory

SUSE-SU-2026:21733-1

Vulnerability from csaf_suse - Published: 2026-05-19 11:42 - Updated: 2026-09-16 19:50

Summary

Security update for dnsmasq

Severity

Important

Scope

7 vulnerabilities in this advisory, including CVE-2026-4891.

CVE-2026-4891

5.3 (Medium)


                
                  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Recommended: 4 products

Open the full advisory

SUSE-SU-2026:21788-1

Vulnerability from csaf_suse - Published: 2026-05-13 16:34 - Updated: 2026-09-16 19:51

Summary

Security update for dnsmasq

Severity

Important

Scope

7 vulnerabilities in this advisory, including CVE-2026-4891.

CVE-2026-4891

5.3 (Medium)


                
                  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Recommended: 16 products

Open the full advisory

SUSE-SU-2026:2458-1

Vulnerability from csaf_suse - Published: 2026-06-18 15:54 - Updated: 2026-09-17 16:23

Summary

Security update for dnsmasq

Severity

Important

Scope

7 vulnerabilities in this advisory, including CVE-2026-4891.

CVE-2026-4891

5.3 (Medium)


                
                  CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Recommended: 17 products

Open the full advisory

UBUNTU-CVE-2026-4891 (CVE-2026-4891)

Vulnerability from osv_ubuntu – Published: 2026-05-11 12:00 – Updated: 2026-06-30 16:18 – Source website

Details

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

5.3 (Medium)


                    
                      CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

7.5 (High)


                    
                      CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-4891	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-4891	REPORT
	https://ubuntu.com/security/notices/USN-8268-1	ADVISORY

JSON

To clipboard

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            "binary_version": "2.90-0ubuntu0.20.04.1+esm2"
          },
          {
            "binary_name": "dnsmasq-base",
            "binary_version": "2.90-0ubuntu0.20.04.1+esm2"
          },
          {
            "binary_name": "dnsmasq-base-lua",
            "binary_version": "2.90-0ubuntu0.20.04.1+esm2"
          },
          {
            "binary_name": "dnsmasq-utils",
            "binary_version": "2.90-0ubuntu0.20.04.1+esm2"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:20.04:LTS",
        "name": "dnsmasq",
        "purl": "pkg:deb/ubuntu/dnsmasq@2.90-0ubuntu0.20.04.1+esm2?arch=source\u0026distro=esm-infra/focal"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.90-0ubuntu0.20.04.1+esm2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.80-1ubuntu2",
        "2.80-1ubuntu4",
        "2.80-1.1ubuntu1",
        "2.80-1.1ubuntu1.2",
        "2.80-1.1ubuntu1.3",
        "2.80-1.1ubuntu1.4",
        "2.80-1.1ubuntu1.5",
        "2.80-1.1ubuntu1.6",
        "2.80-1.1ubuntu1.7",
        "2.90-0ubuntu0.20.04.1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "dnsmasq",
            "binary_version": "2.90-0ubuntu0.22.04.3"
          },
          {
            "binary_name": "dnsmasq-base",
            "binary_version": "2.90-0ubuntu0.22.04.3"
          },
          {
            "binary_name": "dnsmasq-base-lua",
            "binary_version": "2.90-0ubuntu0.22.04.3"
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          {
            "binary_name": "dnsmasq-utils",
            "binary_version": "2.90-0ubuntu0.22.04.3"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:22.04:LTS",
        "name": "dnsmasq",
        "purl": "pkg:deb/ubuntu/dnsmasq@2.90-0ubuntu0.22.04.3?arch=source\u0026distro=jammy"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "2.90-0ubuntu0.22.04.3"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "2.85-1ubuntu2",
        "2.86-1.1",
        "2.86-1.1ubuntu0.1",
        "2.86-1.1ubuntu0.2",
        "2.86-1.1ubuntu0.3",
        "2.86-1.1ubuntu0.4",
        "2.86-1.1ubuntu0.5",
        "2.90-0ubuntu0.22.04.1"
      ]
    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
        "binaries": [
          {
            "binary_name": "dnsmasq",
            "binary_version": "2.90-2ubuntu0.3"
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            "binary_name": "dnsmasq-base",
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            "binary_name": "dnsmasq-base-lua",
            "binary_version": "2.90-2ubuntu0.3"
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      "package": {
        "ecosystem": "Ubuntu:24.04:LTS",
        "name": "dnsmasq",
        "purl": "pkg:deb/ubuntu/dnsmasq@2.90-2ubuntu0.3?arch=source\u0026distro=noble"
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        {
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            {
              "introduced": "0"
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        }
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      "versions": [
        "2.89-1",
        "2.90-2",
        "2.90-2build1",
        "2.90-2build2",
        "2.90-2ubuntu0.1"
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    {
      "ecosystem_specific": {
        "availability": "No subscription required",
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            "binary_name": "dnsmasq",
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            "binary_name": "dnsmasq-base",
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      "package": {
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    },
    {
      "ecosystem_specific": {
        "availability": "No subscription required",
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          {
            "binary_name": "dnsmasq",
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            "binary_name": "dnsmasq-base",
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          {
            "binary_name": "dnsmasq-base-lua",
            "binary_version": "2.92-1ubuntu0.2"
          },
          {
            "binary_name": "dnsmasq-utils",
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          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:26.04:LTS",
        "name": "dnsmasq",
        "purl": "pkg:deb/ubuntu/dnsmasq@2.92-1ubuntu0.2?arch=source\u0026distro=resolute"
      },
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      ],
      "versions": [
        "2.91-1build1",
        "2.92~rc3-1",
        "2.92-1"
      ]
    }
  ],
  "aliases": [],
  "details": "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.",
  "id": "UBUNTU-CVE-2026-4891",
  "modified": "2026-06-30T16:18:36Z",
  "published": "2026-05-11T12:00:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-4891"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-4891"
    },
    {
      "type": "ADVISORY",
      "url": "https://ubuntu.com/security/notices/USN-8268-1"
    }
  ],
  "related": [
    "USN-8268-1"
  ],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-4891"
  ]
}

WID-SEC-W-2026-1468

Vulnerability from csaf_certbund - Published: 2026-05-11 22:00 - Updated: 2026-08-05 22:00

Summary

dnsmasq: Mehrere Schwachstellen

Severity

Hoch

Scope

6 vulnerabilities in this advisory, including CVE-2026-4891.

CVE-2026-4891

Known affected: 11 products

Open the full advisory

Sightings

Author	Source	Type	Date	Other

Nomenclature

Seen: The vulnerability was mentioned, discussed, or observed by the user.
Confirmed: The vulnerability has been validated from an analyst's perspective.
Published Proof of Concept: A public proof of concept is available for this vulnerability.
Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
Not confirmed: The user expressed doubt about the validity of the vulnerability.
Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.

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The MITRE ATT&CK techniques below are AI-generated suggestions, inferred from the description of the vulnerability by the CIRCL/vulnerability-attack-technique-classification-roberta-base model, served locally by ML-Gateway. They have not been verified by an analyst and are provided for guidance only.
The approach is described in our paper Mapping CVEs to MITRE ATT&CK Techniques: A Curated Gold-Set Classifier and the Limits of LLM-Assisted Label Expansion.
Browse all ATT&CK techniques and the vulnerabilities related to each.

Related by attack behaviour

Vulnerabilities whose description is nearest to this one in the vector space of the CIRCL/vulnerability-attack-technique-biencoder model. This is a similarity search over the bi-encoder space (plain cosine), not a classification, and it has no measured accuracy.

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CVE-2026-4891 (GCVE-0-2026-4891)

UBUNTU-CVE-2026-4891 (CVE-2026-4891)

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