CVE-2026-19401Remote UDP DoS by sending multiple DNS Cookie options
Updated under an hour ago ()
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It affects NLnet Labs NSD and 1 other product. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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Free account, 1 product
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.
- CVSS
- 8.2 HIGH (v4.0, CNA)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
- Weakness (CWE)
- CWE-617, CWE-400
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- NLnet Labs
- NVD analysis
- Analyzed
- Record last updated
- Aug 26, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
NLnet Labs NSD nlnet_labs:nsd (from the name) | from 4.3.7 before 4.15.1 | CNA record |
nlnetlabs nsd nlnetlabs:nsd | from 4.3.7 before 4.15.1 | NVD |
References
- https://www.nlnetlabs.nl/downloads/nsd/CVE-2026-19401.txtvendor-advisory
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.