Quick answers
- Is CVE-2026-18916 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-18916 being exploited in the wild.
- How severe is CVE-2026-18916?
- High severity, with a CVSS score of 7.5, published 26 August 2026.
- Which products and versions are affected?
- NLnet Labs NSD 3.2.11 to 4.15.0.
- Is there a fix for CVE-2026-18916?
- A patch was published on 2026-08-26: NSD 4.15.1 released with patch; manual patch available for 4.15.0 Junglewise finds every place you run it, drafts the upgrade and applies it once you approve.
- How is CVE-2026-18916 attacked?
- It is attacked over the network, in a hosted service.
- Am I affected by CVE-2026-18916?
- Check whether you run Nlnetlabs Nsd. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
This is a denial-of-service vulnerability in NSD's TCP query handling. The vulnerability occurs when a remote client throttles the TCP receive window (to 1 byte) after sending a TCP DNS query, causing the server child process to crash. No authentication is required; any remote network client can exploit this by repeatedly crashing NSD child processes, eventually denying all TCP service to the NSD instance. The vulnerability affects NSD versions 3.2.11 through 4.15.0. Patches are available: NSD 4.15.1 includes the fix, and a manual patch is available for version 4.15.0.
Affected products
- NLnet Labs NSD 3.2.11 to 4.15.0
Timeline
- 2026-08-26: disclosed
- 2026-08-26: patched: NSD 4.15.1 released with patch; manual patch available for 4.15.0