# CVE-2026-19401

## Summary

- **CVE ID:** CVE-2026-19401
- **Severity:** HIGH
- **CVSS Score:** 8.2 (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)
- **CWE:** CWE-617, CWE-400
- **Published:** Aug 26, 2026
- **Last Modified:** Aug 26, 2026

## 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.

## Affected Products

- NLnet Labs — NSD (4.3.7)

## References

- [CNA](https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-19401.txt)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.36%
- **EPSS Percentile:** 29.0

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-10._