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No exploitation reportedFix available

CVE-2026-19401

No exploitation reported by the sources we read.

  • Published2026-08-26
  • Fixed in4.15.1
  • WeaknessCWE-400 · CWE-617

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

Description

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.

Timeline

dates in UTC
  1. 2026-08-2609:16CVE publishedNVD

Versions per branch

NVD
Nlnetlabs nsd
BranchAffectedFixed in
4.x≥ 4.3.7, < 4.15.14.15.1

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As NLnet Labs, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • NLnet Labs NSDother versions: not affected
    Affected
    • ≥ 4.3.7, < 4.15.1fixed in 4.15.1semver

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-08-26

Distribution builds and vendor advisories

Packages from OSV.dev and products from the vendors' CSAF advisories.

version not verifiedVersions not verified: read as OSV.dev and the vendors publish them, not checked against each vendor's release list.

Packages

  • nsdUbuntu:Pro:26.04:LTSall versions · no fixed version listed
  • nsdUbuntu:Pro:24.04:LTSall versions · no fixed version listed
  • nsdUbuntu:Pro:22.04:LTSall versions · no fixed version listed
  • nsdUbuntu:Pro:20.04:LTSall versions · no fixed version listed
  • nsdUbuntu:Pro:18.04:LTSall versions · no fixed version listed
  • nsdUbuntu:Pro:16.04:LTSall versions · no fixed version listed
  • nsdUbuntu:26.10all versions · no fixed version listed
  • nsdDebian:14all versions · fixed in 4.15.1-1

2 more package ranges on OSV.dev

Vendor advisories

  • CVE-2026-19401 Red Hat Product Security

    nsd: NSD: Remote denial of service via crafted DNS Cookie options

Full record on NVD

Fix

  1. Update Nlnetlabs nsd to 4.15.1

Advisories and patches

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

  • CISA-ADPSSVC decisionnone2026-08-26
  • CNACVSS 4.08.2known since 2026-10-23
  • NVDCVSS 3.17.5read 2026-10-23
  • CNAweakness (CWE)CWE-400, CWE-617known since 2026-10-23
  • FIRST EPSSEPSS score0.5 %2026-11-09
  • OSVaffected packages—
  • GitHub Advisoriesadvisory—

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
CVSS 4.0 vector
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/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:X
Published
2026-08-26
Last Modified
2026-09-08
NVD status
Analyzed
GitHub Advisory
GHSA-v29p-5fvf-m7p8

Frequently asked questions

What is CVE-2026-19401?

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.

Is CVE-2026-19401 actively exploited?

Active exploitation of CVE-2026-19401 has not been confirmed. Its EPSS score was 0.5% on 2026-11-09, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-19401?

CVE-2026-19401 has a CVSS v3 base score of 7.5 (HIGH severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.

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