CVE-2026-19401
Remote UDP DoS by sending multiple DNS Cookie options
- State
- Published
- Severity
- 8.2 High
- Published
- Aug 26, 2026
- Updated
- Aug 26, 2026
- Reserved
- Aug 10, 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.
Scores
| CVSS | Score | Vector | Source |
|---|---|---|---|
| 4.0 | 8.2 High | 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 | NLnet Labs |
Weaknesses
Affected Products
| Product | Versions |
|---|---|
NSDNLnet Labs |
|
References
- https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-19401.txtvendor-advisory
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