7.5highHigh
CVE-2026-19401
Nlnetlabs Nsd
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.
Exploitation status
- A vendor advisory or patch reference has been published.
What the metrics mean
- It is reachable over a network, without needing local access.
- For an attacker who can reach it, no special conditions are needed to exploit it.
- To exploit it, no account is needed.
- Beyond that, no action by a user is required.
Scoring
- CVSS
- 7.5 (v3.1)
- Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H- CVSS v4
- 8.2
- Weakness
- CWE-400
- Assigned by
- sep@nlnetlabs.nl
Dates
- Published
- 2026-08-26
- Last modified
- 2026-09-08
- Sources
- NVD
Affected products
- Nlnetlabs Nsd4.3.7 - 4.15.1
As listed in the NVD configuration data. Not a statement about your estate.