# CVE-2026-19401: nsd: Any remote client can crash a (debugging/non-release build type) NSD serve child by sending it a special crafted mess...

CVE-2026-19401 is fixed in nsd on 1 platform by DEBIAN-CVE-2026-19401 (version 4.15.1-1), released September 4, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-19401
- Priority: High
- CVSS: 7.5 (high)
- EPSS: 0.0046
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: 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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | nsd Debian 14 | 4.15.1-1 | [DEBIAN-CVE-2026-19401](https://patchblox.com/security/data/fix/linux/debian-cve-2026-19401.md) | Sep 4, 2026 |

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Data as of 2026-11-08T13:06:02Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

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