Security advisory

{
  "id": "7011ed37c5d86cbbe90eeb86a191fd48174b1c92c94981d3908c8dec0c50a22f",
  "url": "https://osv.dev/vulnerability/CVE-2020-26521",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2020-26521",
    "summary": "The JWT library in NATS nats-server before 2.1.9 allows a denial of service (a nil dereference in Go code).",
    "evidence": "osv:CVE-2020-26521",
    "products": [],
    "severity": "high",
    "structured": {
      "id": "CVE-2020-26521",
      "aliases": [
        "CVE-2020-26521",
        "GHSA-h2fg-54x9-5qhq",
        "GHSA-hmm9-r2m2-qg9w",
        "GO-2022-0402"
      ],
      "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/nats-io/nats-server",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "7c7662603115c1f53a9bacfa0115893c8ebe6fd4"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:linuxfoundation:nats-server:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.1.9"
                      }
                    ],
                    "source": "CPE_RANGE"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v2.1.8",
            "v2.1.7",
            "v2.1.6",
            "v2.1.4",
            "v2.1.2",
            "v2.1.0",
            "v2.0.4",
            "v2.0.2",
            "v2.0.0",
            "v2.0.0-RC19",
            "v2.0.0-RC14",
            "v1.3.0",
            "v1.2.0",
            "v1.1.0",
            "v1.0.6",
            "v1.0.4",
            "v1.0.2",
            "v1.0.0",
            "v0.9.6",
            "v0.9.4",
            "v0.9.2",
            "v0.8.1",
            "v0.8.0",
            "v0.7.2",
            "v0.7.0",
            "v0.6.8",
            "v0.6.6",
            "v0.6.4",
            "v0.6.2",
            "v0.6.0",
            "v0.5.6",
            "v0.5.4",
            "v0.5.2",
            "v0.5.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2020-26521.json"
          }
        }
      ],
      "modified": "2026-10-20T10:52:58.053017232Z",
      "provider": "osv",
      "references": [
        "https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/VT67XCLIIBYRT762SVFBYFFTQFVSM3SI/",
        "https://github.com/nats-io/nats-server/commits/master"
      ],
      "provider_metadata": {
        "unresolved_ranges": [
          {
            "cpes": [
              "cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:*"
            ],
            "vendor_product": "fedoraproject:fedora",
            "extracted_events": [
              {
                "range": [
                  {
                    "introduced": "33"
                  },
                  {
                    "last_affected": "33"
                  }
                ],
                "source": "CPE_STRING"
              }
            ]
          }
        ]
      }
    },
    "related_cves": [
      {
        "value": "CVE-2020-26521",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 384100,
  "published_at": "2020-11-06T08:15:13.563+00:00"
}