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knot-resolver — security advisory

Type: advisorySources: OSVAdvisory ID: DEBIAN-CVE-2020-12667

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.

Products
knot-resolver
Affected versions
Not specified
Fixed versions
5.1.1-0.1
CVEs
CVE-2020-12667
Confirmed fixed CVEs
Not specified
Updated in this feed
1 Nov 2026, 12:33 UTC · Revision 1

Source evidence

DEBIAN-CVE-2020-12667

core-osv · Original source

Published 19 May 2020, 13:15 UTC

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.

osv:DEBIAN-CVE-2020-12667

knot-resolver

Fixed versions: 5.1.1-0.1

knot-resolver

Fixed versions: 5.1.1-0.1

knot-resolver

Fixed versions: 5.1.1-0.1

Complete source record
{
  "id": "05c9753b740816c4f49a5be39f9ef1a1f10e3789f4a532b94cbd8c99e22cfc01",
  "url": "https://osv.dev/vulnerability/DEBIAN-CVE-2020-12667",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "DEBIAN-CVE-2020-12667",
    "summary": "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.",
    "evidence": "osv:DEBIAN-CVE-2020-12667",
    "products": [
      {
        "name": {
          "value": "knot-resolver",
          "evidence": "/affected/0/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.1.1-0.1",
            "evidence": "/affected/0/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "knot-resolver",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.1.1-0.1",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      },
      {
        "name": {
          "value": "knot-resolver",
          "evidence": "/affected/2/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.1.1-0.1",
            "evidence": "/affected/2/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "high",
    "structured": {
      "id": "DEBIAN-CVE-2020-12667",
      "aliases": [
        "DEBIAN-CVE-2020-12667"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "5.1.1-0.1"
                }
              ]
            }
          ],
          "package": {
            "name": "knot-resolver",
            "purl": "pkg:deb/debian/knot-resolver?arch=source&distro=bookworm",
            "ecosystem": "Debian:12"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-12667.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "5.1.1-0.1"
                }
              ]
            }
          ],
          "package": {
            "name": "knot-resolver",
            "purl": "pkg:deb/debian/knot-resolver?arch=source&distro=trixie",
            "ecosystem": "Debian:13"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-12667.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "5.1.1-0.1"
                }
              ]
            }
          ],
          "package": {
            "name": "knot-resolver",
            "purl": "pkg:deb/debian/knot-resolver?arch=source&distro=forky",
            "ecosystem": "Debian:14"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/debian-osv/debian-cve-osv/DEBIAN-CVE-2020-12667.json"
          },
          "ecosystem_specific": {
            "urgency": "not yet assigned"
          }
        }
      ],
      "modified": "2026-10-26T12:00:29.440062667Z",
      "provider": "osv",
      "upstream": [
        "CVE-2020-12667"
      ],
      "references": [
        "https://security-tracker.debian.org/tracker/CVE-2020-12667"
      ]
    },
    "related_cves": [
      {
        "value": "CVE-2020-12667",
        "evidence": "/upstream"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 451178,
  "published_at": "2020-05-19T13:15:11.763+00:00"
}