CVE-2026-19401
Fixed in a distro release EPSS <1%CVSS 8.2
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.
Products: NLnet Labs NSD
Distro releases
| Release | Package | Fixed in |
|---|---|---|
| Debian 12 | nsd | no fix |
| Debian 13 | nsd | no fix |
| Debian 14 | nsd | 4.15.1-1 |
| Ubuntu 26.10 | nsd | no fix |
| Ubuntu Pro 16.04 LTS | nsd | no fix |
| Ubuntu Pro 18.04 LTS | nsd | no fix |
| Ubuntu Pro 20.04 LTS | nsd | no fix |
| Ubuntu Pro 22.04 LTS | nsd | no fix |
| Ubuntu Pro 24.04 LTS | nsd | no fix |
| Ubuntu Pro 26.04 LTS | nsd | no fix |