Description
Any remote client can crash a NSD serve child, by throttling the TCP receive window after a TCP query. By continuously crashing the serve childs, the remote client can denial all TCP service to this NSD instance.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| NLnet Labs | NSD | 3.2.11 – < 4.15.1 | 4.15.1 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | nsd | 4.15.1-1 | — |
| Debian 13 | nsd | No fix yet | — |
| Debian 12 | nsd | No fix yet | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.10 | nsd | No fix yet | — |
Show 6 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu Pro 26.04 LTS | nsd | No fix yet | — |
| Ubuntu Pro 24.04 LTS | nsd | No fix yet | — |
| Ubuntu Pro 22.04 LTS | nsd | No fix yet | — |
| Ubuntu Pro 20.04 LTS | nsd | No fix yet | — |
| Ubuntu Pro 18.04 LTS | nsd | No fix yet | — |
| Ubuntu Pro 16.04 LTS | nsd | No fix yet | — |
Advisories 1
- WID-SEC-2026-3663 OpenBSD: Mehrere Schwachstellen BSI CERT-Bund (WID) · Sep 29, 2026
References
- https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-18916.txt vendor-advisory