Security advisory

{
  "id": "a05442246c80f26f5464c8de6ac847d8746ed23b708b69b51d67fd693b3fad46",
  "url": "https://osv.dev/vulnerability/CVE-2020-12667",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "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:CVE-2020-12667",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2020-12667",
      "aliases": [
        "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": [
            {
              "repo": "https://github.com/cz-nic/knot-resolver",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "24f5932a12484446bb9e88a52c6c36cfa6cb1afe"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:nic:knot_resolver:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "5.1.1"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v5.1.0",
            "v5.0.1",
            "v5.0.0",
            "v4.3.0",
            "v4.2.2",
            "v4.2.0",
            "v4.1.0",
            "v4.0.0",
            "v3.2.1",
            "v3.2.0",
            "v3.1.0",
            "v3.0.0",
            "v2.4.0",
            "v2.3.0",
            "v2.2.0",
            "v2.1.1",
            "v2.1.0",
            "v2.0.0",
            "v1.5.1",
            "v1.5.0",
            "v1.4.0",
            "v1.3.3",
            "v1.3.2",
            "v1.3.1",
            "v1.3.0",
            "v1.2.6",
            "v1.2.1",
            "v1.2.0",
            "v1.2.0-rc3",
            "v1.2.0-rc2",
            "v1.2.0-rc1",
            "v1.1.1",
            "v1.1.0",
            "v1.0.0",
            "v1.0.0-beta3",
            "v1.0.0-beta2",
            "v1.0.0-beta1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2020-12667.json"
          }
        }
      ],
      "modified": "2026-10-24T10:30:58.392503938Z",
      "provider": "osv",
      "references": [
        "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://en.blog.nic.cz/2020/05/19/nxnsattack-upgrade-resolvers-to-stop-new-kind-of-random-subdomain-attack/",
        "https://www.knot-resolver.cz/2020-05-19-knot-resolver-5.1.1.html"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2020-12667",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 439083,
  "published_at": "2020-05-19T13:15:11.763+00:00"
}