Vulnerability-Lookup

CVE-2026-19401 (GCVE-0-2026-19401)

Vulnerability from cvelistv5 – Published: 2026-08-26 08:44 – Updated: 2026-08-26 14:16

Title

Remote UDP DoS by sending multiple DNS Cookie options

Summary

Any remote client can crash a (debugging/non-release build type) NSD serve child by sending it a special crafted message with a specially tuned number of DNS Cookie options (17 when UDP payload size is 512). By continuously crashing the serve childs, the remote client can severely hamper or, when positioned sufficiently close, deny all DNS service.

Severity

8.2 (High)


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

SSVC

Exploitation: none Automatable: no Technical Impact: partial

CISA Coordinator · CISA-ADP (v2.0.3)

Decision recorded 2026-08-26 14:09 UTC

CWE

CWE-617 - Reachable Assertion
CWE-400 - Uncontrolled Resource Consumption

Assigner

NLnet Labs

References

1 reference

URL	Tags
https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-1…	vendor-advisory

Impacted products

1 product

Vendor	Product	Version	CPE status
NLnet Labs	NSD	Affected: 4.3.7 , < 4.15.1 (semver)	guessed

Date Public

2026-08-26 12:00

Credits

Qifan Zhang from Palo Alto Networks afldl <zhangph@yandex.com>

Show details on NVD website

JSON

To clipboard

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FKIE_CVE-2026-19401

Vulnerability from fkie_nvd - Published: 2026-08-26 09:16 - Updated: 2026-08-26 15:16

Severity

8.2 (High) - CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N

Summary

References

	URL	Tags
	sep@nlnetlabs.nl	https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-19401.txt

Impacted products

	Vendor	Product	Version

JSON

To clipboard

{
  "affected": [
    {
      "affectedData": [
        {
          "defaultStatus": "unaffected",
          "product": "NSD",
          "vendor": "NLnet Labs",
          "versions": [
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    }
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ubuntu-cve-2026-19401

Vulnerability from osv_ubuntu

Published

2026-08-27 00:00

Modified

2026-08-27 00:00

Summary

Details

(Any remote client can crash a (debugging/non-release build type) NSD s ...)

Severity

8.2 (High)


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

N/A (UNKNOWN)


                    
                      medium

References

URL

Type

	https://ubuntu.com/security/CVE-2026-19401	REPORT
	https://www.cve.org/CVERecord?id=CVE-2026-19401	REPORT

JSON

To clipboard

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  "affected": [
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "nsd",
            "binary_version": "4.1.7-1ubuntu0.1~esm1"
          },
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      },
      "package": {
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    },
    {
      "ecosystem_specific": {
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          {
            "binary_name": "nsd",
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          }
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      },
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    },
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      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "4.3.5-1",
        "4.3.7-1",
        "4.3.8-1",
        "4.3.8-1build1",
        "4.3.9-1",
        "4.3.9-1ubuntu0.1~esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "nsd",
            "binary_version": "4.8.0-1ubuntu0.1~esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:24.04:LTS",
        "name": "nsd",
        "purl": "pkg:deb/ubuntu/nsd@4.8.0-1ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/noble"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "4.7.0-1",
        "4.8.0-1",
        "4.8.0-1build1",
        "4.8.0-1build3",
        "4.8.0-1ubuntu0.1~esm1"
      ]
    },
    {
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "nsd",
            "binary_version": "4.14.0-1ubuntu0.1~esm1"
          }
        ]
      },
      "package": {
        "ecosystem": "Ubuntu:Pro:26.04:LTS",
        "name": "nsd",
        "purl": "pkg:deb/ubuntu/nsd@4.14.0-1ubuntu0.1~esm1?arch=source\u0026distro=esm-apps/resolute"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "0"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ],
      "versions": [
        "4.12.0-1",
        "4.13.0-6",
        "4.14.0-1",
        "4.14.0-1ubuntu0.1~esm1"
      ]
    }
  ],
  "aliases": [],
  "details": "(Any remote client can crash a (debugging/non-release build type) NSD s ...)",
  "id": "UBUNTU-CVE-2026-19401",
  "modified": "2026-08-27T00:00:00Z",
  "published": "2026-08-27T00:00:00Z",
  "references": [
    {
      "type": "REPORT",
      "url": "https://ubuntu.com/security/CVE-2026-19401"
    },
    {
      "type": "REPORT",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-19401"
    }
  ],
  "related": [],
  "schema_version": "1.7.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    },
    {
      "score": "medium",
      "type": "Ubuntu"
    }
  ],
  "upstream": [
    "CVE-2026-19401"
  ]
}

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.

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.

Action not permitted

CVE-2026-19401 (GCVE-0-2026-19401)

FKIE_CVE-2026-19401

ubuntu-cve-2026-19401

Vulnerability from osv_ubuntu

Tags

Sightings

Nomenclature