Description
Knot Resolver before 5.1.1 allows traffic amplification via a crafted DNS answer from an attacker-controlled server, aka an "NXNSAttack" issue. This is triggered by random subdomains in the NSDNAME in NS records.
Metrics
CVSS 3.1 7.5/10
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:HWeakness enumeration
Affected software
| Vendor | Product | Versions |
|---|---|---|
| n/a | n/a | n/a |
| nic | knot_resolver | - |
References
- http://cyber-security-group.cs.tau.ac.il/#Technical Description, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2020/05/19/2Mailing List, Third Party Advisory
- https://en.blog.nic.cz/2020/05/19/nxnsattack-upgrade-resolvers-to-stop-new-kind-of-random-subdomain-attack/Technical Description, Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2024/04/msg00017.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/76Y4FITMOH6RVPWAANGV7NB2ZHPJJGDQ/
- https://www.knot-resolver.cz/2020-05-19-knot-resolver-5.1.1.htmlRelease Notes, Vendor Advisory
- http://cyber-security-group.cs.tau.ac.il/#Technical Description, Third Party Advisory
- http://www.openwall.com/lists/oss-security/2020/05/19/2Mailing List, Third Party Advisory
- https://en.blog.nic.cz/2020/05/19/nxnsattack-upgrade-resolvers-to-stop-new-kind-of-random-subdomain-attack/Technical Description, Vendor Advisory
- https://lists.debian.org/debian-lts-announce/2024/04/msg00017.html
- https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/76Y4FITMOH6RVPWAANGV7NB2ZHPJJGDQ/
- https://www.knot-resolver.cz/2020-05-19-knot-resolver-5.1.1.htmlRelease Notes, Vendor Advisory
Timeline
- Published
- May 19, 2020
- Last modified
- Jun 17, 2026
- NVD status
- Modified