CVE catalog

CVE-2026-42944

NLnet Labs Unbound 1.14.0 up to and including version…

NLnet Labs Unbound 1.14.0 up to and including version 1.25.0 has a vulnerability that results in heap overflow when encoding multiple NSID and/or DNS Cookie EDNS and/or EDNS Padding options in the reply packet. The relevant options ('nsid', 'answer-cookie', 'pad-responses' (default)) need to be enabled for the vulnerability to be exploited. An adversary who can query Unbound can exploit the vulnerability by attaching multiple NSID and/or DNS Cookie EDNS and/or EDNS Padding options to the query. A flaw in the size calculation of the EDNS field truncates the correct value which allows the encoder to overflow the available space when writing. Those two combined lead to a heap overflow write of Unbound controlled data and eventually a crash. Unbound 1.25.1 contains a patch with a fix to de-duplicate the EDNS options and a fix to prevent truncation of the EDNS field size calculation.

Severity: High · CVSS 8.7
Published: May 19, 2026, 10:00:00 PM UTC
Source: [NVD] · [CVE record]
EPSS: 0.84% · Oct 27, 2026

Projects and upstream resources

[unbound][Source-reported homepage]

Reported versions and fixes

Each observation applies to its named package, distribution, and release. Distribution backports can fix a vulnerability while retaining an older upstream version number.

Version impact has not been established. The original provider fields are retained below.

Provider details and historical evidence

Original provider fields

{
  "package_releases": [
    {
      "name": "unbound",
      "status": "fixed",
      "release": "sid",
      "version": "1.26.2-1"
    },
    {
      "name": "unbound",
      "status": "fixed",
      "release": "forky",
      "version": "1.26.2-1"
    },
    {
      "name": "unbound",
      "status": "fixed",
      "release": "trixie",
      "version": "1.22.0-2+deb13u3"
    },
    {
      "name": "unbound",
      "status": "fixed",
      "release": "trixie-security",
      "version": "1.26.2-0+deb13u1"
    },
    {
      "name": "unbound",
      "status": "vulnerable",
      "release": "bookworm",
      "version": "1.17.1-2+deb12u4"
    },
    {
      "name": "unbound",
      "status": "vulnerable",
      "release": "bookworm-security",
      "version": "1.17.1-2+deb12u3"
    }
  ],
  "fixed_versions": [
    {
      "bug": 1137187,
      "name": "unbound",
      "type": "source",
      "origin": null,
      "release": "sid",
      "urgency": "not yet assigned",
      "fixed_version": "1.25.1-1"
    },
    {
      "bug": 1137187,
      "name": "unbound",
      "type": "source",
      "origin": null,
      "release": "forky",
      "urgency": "not yet assigned",
      "fixed_version": "1.25.1-1"
    },
    {
      "bug": 1137187,
      "name": "unbound",
      "type": "source",
      "origin": null,
      "release": "trixie",
      "urgency": "not yet assigned",
      "fixed_version": "1.22.0-2+deb13u3"
    },
    {
      "bug": 1137187,
      "name": "unbound",
      "type": "source",
      "origin": null,
      "release": "bookworm",
      "urgency": "not yet assigned",
      "fixed_version": ""
    }
  ],
  "distribution_packages": [
    {
      "name": "unbound",
      "ecosystem": "cpe",
      "fixed_version": "1.19.2-1ubuntu3.8"
    },
    {
      "name": "libunbound-dev",
      "ecosystem": "cpe",
      "fixed_version": "1.19.2-1ubuntu3.8"
    },
    {
      "name": "libunbound8",
      "ecosystem": "cpe",
      "fixed_version": "1.19.2-1ubuntu3.8"
    },
    {
      "name": "python3-unbound",
      "ecosystem": "cpe",
      "fixed_version": "1.19.2-1ubuntu3.8"
    },
    {
      "name": "unbound-anchor",
      "ecosystem": "cpe",
      "fixed_version": "1.19.2-1ubuntu3.8"
    },
    {
      "name": "unbound-host",
      "ecosystem": "cpe",
      "fixed_version": "1.19.2-1ubuntu3.8"
    },
    {
      "name": "unbound",
      "ecosystem": "cpe",
      "fixed_version": "not yet fixed"
    },
    {
      "name": "unbound",
      "ecosystem": "cpe",
      "fixed_version": "1.25.1"
    },
    {
      "name": "unbound",
      "distro": "alpine",
      "ranges": [
        {
          "type": "ECOSYSTEM",
          "events": [
            {
              "introduced": "1.14.0"
            },
            {
              "fixed": "1.25.2-r0"
            }
          ]
        }
      ],
      "release": "3.22",
      "versions": [],
      "ecosystem": "apk",
      "fixed_version": "1.25.2-r0",
      "provider_record_id": "ALPINE-CVE-2026-42944"
    },
    {
      "name": "unbound",
      "distro": "alpine",
      "ranges": [
        {
          "type": "ECOSYSTEM",
          "events": [
            {
              "introduced": "1.14.0"
            },
            {
              "fixed": "1.25.2-r0"
            }
          ]
        }
      ],
      "release": "3.23",
      "versions": [],
      "ecosystem": "apk",
      "fixed_version": "1.25.2-r0",
      "provider_record_id": "ALPINE-CVE-2026-42944"
    },
    {
      "name": "unbound",
      "distro": "alpine",
      "ranges": [
        {
          "type": "ECOSYSTEM",
          "events": [
            {
              "introduced": "1.14.0"
            },
            {
              "fixed": "1.25.1-r0"
            }
          ]
        }
      ],
      "release": "3.24",
      "versions": [],
      "ecosystem": "apk",
      "fixed_version": "1.25.1-r0",
      "provider_record_id": "ALPINE-CVE-2026-42944"
    },
    {
      "name": "unbound",
      "distro": "ubuntu",
      "ranges": [
        {
          "type": "ECOSYSTEM",
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.19.2-1ubuntu3.8"
            }
          ]
        }
      ],
      "release": "24.04",
      "versions": [
        "1.17.1-2",
        "1.18.0-2ubuntu1",
        "1.18.0-2ubuntu2",
        "1.19.1-1ubuntu1",
        "1.19.2-1ubuntu1",
        "1.19.2-1ubuntu3",
        "1.19.2-1ubuntu3.1",
        "1.19.2-1ubuntu3.2",
        "1.19.2-1ubuntu3.3",
        "1.19.2-1ubuntu3.4",
        "1.19.2-1ubuntu3.5",
        "1.19.2-1ubuntu3.6",
        "1.19.2-1ubuntu3.7"
      ],
      "ecosystem": "deb",
      "fixed_version": "1.19.2-1ubuntu3.8",
      "provider_record_id": "UBUNTU-CVE-2026-42944"
    },
    {
      "name": "unbound",
      "distro": "ubuntu",
      "ranges": [
        {
          "type": "ECOSYSTEM",
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.22.0-2ubuntu2.3"
            }
          ]
        }
      ],
      "release": "25.10",
      "versions": [
        "1.22.0-1ubuntu1",
        "1.22.0-2ubuntu1",
        "1.22.0-2ubuntu2",
        "1.22.0-2ubuntu2.1",
        "1.22.0-2ubuntu2.2"
      ],
      "ecosystem": "deb",
      "fixed_version": "1.22.0-2ubuntu2.3",
      "provider_record_id": "UBUNTU-CVE-2026-42944"
    },
    {
      "name": "unbound",
      "distro": "ubuntu",
      "ranges": [
        {
          "type": "ECOSYSTEM",
          "events": [
            {
              "introduced": "0"
            },
            {
              "fixed": "1.24.2-1ubuntu2.1"
            }
          ]
        }
      ],
      "release": "26.04",
      "versions": [
        "1.22.0-2ubuntu2",
        "1.22.0-2ubuntu4",
        "1.24.2-1ubuntu1",
        "1.24.2-1ubuntu2"
      ],
      "ecosystem": "deb",
      "fixed_version": "1.24.2-1ubuntu2.1",
      "provider_record_id": "UBUNTU-CVE-2026-42944"
    }
  ]
}

[Debian bug #1137187]

OpenFactory catalog packages

Matching against OpenFactory catalog package versions is in progress.

[Debian 12 (Bookworm)]

[libunbound8]Unknown
Source package: [unbound]
Details (4)
- 1.17.1-2+deb12u4 · amd64 · bookworm
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
- 1.17.1-2+deb12u4 · arm64 · bookworm
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
- 1.17.1-2+deb12u3 · amd64 · bookworm-security
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
- 1.17.1-2+deb12u3 · arm64 · bookworm-security
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
[libunbound-dev]Unknown
Source package: [unbound]
Details (4)
- 1.17.1-2+deb12u4 · amd64 · bookworm
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
- 1.17.1-2+deb12u4 · arm64 · bookworm
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
- 1.17.1-2+deb12u3 · amd64 · bookworm-security
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
- 1.17.1-2+deb12u3 · arm64 · bookworm-security
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
[python3-unbound]Unknown
Source package: [unbound]
Details (4)
- 1.17.1-2+deb12u4 · amd64 · bookworm
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
- 1.17.1-2+deb12u4 · arm64 · bookworm
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
- 1.17.1-2+deb12u3 · amd64 · bookworm-security
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
- 1.17.1-2+deb12u3 · arm64 · bookworm-security
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
[unbound]Unknown
Details (4)
- 1.17.1-2+deb12u4 · amd64 · bookworm
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
- 1.17.1-2+deb12u4 · arm64 · bookworm
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
- 1.17.1-2+deb12u3 · amd64 · bookworm-security
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
- 1.17.1-2+deb12u3 · arm64 · bookworm-security
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
[unbound-anchor]Unknown
Source package: [unbound]
Details (4)
- 1.17.1-2+deb12u4 · amd64 · bookworm
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
- 1.17.1-2+deb12u4 · arm64 · bookworm
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
- 1.17.1-2+deb12u3 · amd64 · bookworm-security
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
- 1.17.1-2+deb12u3 · arm64 · bookworm-security
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
[unbound-host]Unknown
Source package: [unbound]
Details (4)
- 1.17.1-2+deb12u4 · amd64 · bookworm
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
- 1.17.1-2+deb12u4 · arm64 · bookworm
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
- 1.17.1-2+deb12u3 · amd64 · bookworm-security
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12
- 1.17.1-2+deb12u3 · arm64 · bookworm-security
  Affected
  nvd · unbound · debian · bookworm; nvd · unbound · debian · 12

[Debian 13 (Trixie)]

[libunbound8]Unknown
Source package: [unbound]
Details (6)
- 1.22.0-2+deb13u3 · amd64 · trixie
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.22.0-2+deb13u3 · amd64 · trixie-security · Historical version
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie-security
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.26.1-0+deb13u1 · amd64 · trixie-security · Historical version
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.26.2-0+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
[libunbound-dev]Unknown
Source package: [unbound]
Details (6)
- 1.22.0-2+deb13u3 · amd64 · trixie
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.22.0-2+deb13u3 · amd64 · trixie-security · Historical version
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie-security
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.26.1-0+deb13u1 · amd64 · trixie-security · Historical version
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.26.2-0+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
[python3-unbound]Unknown
Source package: [unbound]
Details (6)
- 1.22.0-2+deb13u3 · amd64 · trixie
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.22.0-2+deb13u3 · amd64 · trixie-security · Historical version
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie-security
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.26.1-0+deb13u1 · amd64 · trixie-security · Historical version
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.26.2-0+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
[unbound]Unknown
Details (6)
- 1.22.0-2+deb13u3 · amd64 · trixie
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.22.0-2+deb13u3 · amd64 · trixie-security · Historical version
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie-security
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.26.1-0+deb13u1 · amd64 · trixie-security · Historical version
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.26.2-0+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
[unbound-anchor]Unknown
Source package: [unbound]
Details (6)
- 1.22.0-2+deb13u3 · amd64 · trixie
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.22.0-2+deb13u3 · amd64 · trixie-security · Historical version
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie-security
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.26.1-0+deb13u1 · amd64 · trixie-security · Historical version
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.26.2-0+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
[unbound-host]Unknown
Source package: [unbound]
Details (6)
- 1.22.0-2+deb13u3 · amd64 · trixie
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.22.0-2+deb13u3 · amd64 · trixie-security · Historical version
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.22.0-2+deb13u3 · arm64 · trixie-security
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.26.1-0+deb13u1 · amd64 · trixie-security · Historical version
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13
- 1.26.2-0+deb13u1 · amd64 · trixie-security
  Fixed · Fixed: 1.22.0-2+deb13u3
  nvd · unbound · debian · 13

Observed: Oct 27, 2026, 7:33:26 AM UTC

References

[CERT-Bund public advisories] · [Debian Security Tracker] · [FIRST EPSS] · [National Vulnerability Database (NVD)] · [OSV Package Vulnerability Database] · [Red Hat security advisories and VEX] · [SUSE security advisories and VEX] · [Ubuntu Security Notices (USN)]