How severe is CVE-2026-19401?

CVE-2026-19401 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.

Is CVE-2026-19401 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2026-19401?

CVE-2026-19401 affects Nlnetlabs Nsd. See the affected-products list for the exact vulnerable versions.

How do I fix CVE-2026-19401?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.

When was CVE-2026-19401 published?

CVE-2026-19401 was published on 2026-08-26 and last updated on 2026-09-08.

CVE-2026-19401

CVE-2026-19401 is a high-severity vulnerability in Nlnetlabs Nsd with a CVSS 3.x base score of 7.5. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-400.

Key facts

Severity: High (CVSS 3.x base score 7.5)
CVSS v4: 8.2
EPSS exploit prediction: 0% (19th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-400
Affected product: Nlnetlabs Nsd
Published: 2026-08-26
Last modified: 2026-09-08

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.

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.
How severe is CVE-2026-19401?: CVE-2026-19401 has a CVSS 3.x base score of 7.5, rated high severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is none, integrity none, and availability high.
Is CVE-2026-19401 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 0% (19th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2026-19401?: CVE-2026-19401 affects Nlnetlabs Nsd. See the affected-products list for the exact vulnerable versions.
How do I fix CVE-2026-19401?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its high severity, prioritise patching exposed systems.
When was CVE-2026-19401 published?: CVE-2026-19401 was published on 2026-08-26 and last updated on 2026-09-08.

References

https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-19401.txt

Affected products (1)

cpe:2.3:a:nlnetlabs:nsd:*:*:*:*:*:*:*:*

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