Vulnerability-Lookup

GHSA-7MMQ-Q3M9-JRV7

Vulnerability from github – Published: 2026-05-20 12:30 – Updated: 2026-05-21 00:30

Details

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 ?

7.5 (High)


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

8.7 (High)


                  
                    CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/U:Red

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{
  "affected": [],
  "aliases": [
    "CVE-2026-42944"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-197"
    ],
    "github_reviewed": false,
    "github_reviewed_at": null,
    "nvd_published_at": "2026-05-20T10:16:27Z",
    "severity": "HIGH"
  },
  "details": "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 (\u0027nsid\u0027, \u0027answer-cookie\u0027, \u0027pad-responses\u0027 (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.",
  "id": "GHSA-7mmq-q3m9-jrv7",
  "modified": "2026-05-21T00:30:27Z",
  "published": "2026-05-20T12:30:36Z",
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42944"
    },
    {
      "type": "WEB",
      "url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-42944.txt"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H",
      "type": "CVSS_V3"
    },
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:Red",
      "type": "CVSS_V4"
    }
  ]
}

CVE-2026-42944 (GCVE-0-2026-42944)

Vulnerability from cvelistv5 – Published: 2026-05-20 09:20 – Updated: 2026-05-20 13:38

Title

Heap overflow with multiple NSID, COOKIE, PADDING EDNS options

Summary

Severity ?

8.7 (High)


                        
                          CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/U:Red

CWE

CWE-197 - Numeric Truncation Error
CWE-787 - Out-of-bounds Write

Assigner

NLnet Labs

References

1 reference

URL	Tags
https://www.nlnetlabs.nl/downloads/unbound/CVE-20…	vendor-advisory

Impacted products

1 product

Vendor	Product	Version
NLnet Labs	Unbound	Affected: 1.14.0 , < 1.25.1 (semver)

Date Public ?

2026-05-20 00:00

Credits

Qifan Zhang (Palo Alto Networks)

Show details on NVD website

JSON

To clipboard

{
  "containers": {
    "adp": [
      {
        "metrics": [
          {
            "other": {
              "content": {
                "id": "CVE-2026-42944",
                "options": [
                  {
                    "Exploitation": "none"
                  },
                  {
                    "Automatable": "yes"
                  },
                  {
                    "Technical Impact": "partial"
                  }
                ],
                "role": "CISA Coordinator",
                "timestamp": "2026-05-20T13:37:32.347565Z",
                "version": "2.0.3"
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              "type": "ssvc"
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        "providerMetadata": {
          "dateUpdated": "2026-05-20T13:38:17.529Z",
          "orgId": "134c704f-9b21-4f2e-91b3-4a467353bcc0",
          "shortName": "CISA-ADP"
        },
        "title": "CISA ADP Vulnrichment"
      }
    ],
    "cna": {
      "affected": [
        {
          "defaultStatus": "unaffected",
          "product": "Unbound",
          "vendor": "NLnet Labs",
          "versions": [
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              "status": "affected",
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              "versionType": "semver"
            }
          ]
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      ],
      "credits": [
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          "type": "finder",
          "value": "Qifan Zhang (Palo Alto Networks)"
        }
      ],
      "datePublic": "2026-05-20T00:00:00.000Z",
      "descriptions": [
        {
          "lang": "en",
          "value": "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 (\u0027nsid\u0027, \u0027answer-cookie\u0027, \u0027pad-responses\u0027 (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."
        }
      ],
      "metrics": [
        {
          "cvssV4_0": {
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            "baseSeverity": "HIGH",
            "vectorString": "CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N/U:Red",
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              "lang": "en",
              "type": "CWE"
            },
            {
              "cweId": "CWE-787",
              "description": "CWE-787: Out-of-bounds Write",
              "lang": "en",
              "type": "CWE"
            }
          ]
        }
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      "providerMetadata": {
        "dateUpdated": "2026-05-20T09:20:23.906Z",
        "orgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6",
        "shortName": "NLnet Labs"
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      "references": [
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          "tags": [
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          "url": "https://www.nlnetlabs.nl/downloads/unbound/CVE-2026-42944.txt"
        }
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      "solutions": [
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          "lang": "en",
          "value": "This issue is fixed starting with version 1.25.1"
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      "timeline": [
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          "time": "2026-04-26T00:00:00.000Z",
          "value": "Issue reported by Qifan Zhang"
        },
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          "lang": "en",
          "time": "2026-04-28T00:00:00.000Z",
          "value": "NLnet Labs shares patch"
        },
        {
          "lang": "en",
          "time": "2026-04-29T00:00:00.000Z",
          "value": "Qifan Zhang verifies patch"
        },
        {
          "lang": "en",
          "time": "2026-05-20T00:00:00.000Z",
          "value": "Fixes released with version 1.25.1"
        }
      ],
      "title": "Heap overflow with multiple NSID, COOKIE, PADDING EDNS options",
      "x_generator": {
        "engine": "cvelib 1.8.0"
      }
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  "cveMetadata": {
    "assignerOrgId": "206fc3a0-e175-490b-9eaa-a5738056c9f6",
    "assignerShortName": "NLnet Labs",
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    "datePublished": "2026-05-20T09:20:23.906Z",
    "dateReserved": "2026-05-07T10:07:51.833Z",
    "dateUpdated": "2026-05-20T13:38:17.529Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}

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.

Detection rules are retrieved from Rulezet.

Action not permitted

GHSA-7MMQ-Q3M9-JRV7

CVE-2026-42944 (GCVE-0-2026-42944)

Tags

Sightings

Nomenclature