Security advisory

{
  "id": "b6501eda0df9bcba911a6778024a8ed2b4f927b56062554ad3b1b0811615e55d",
  "url": "https://osv.dev/vulnerability/CVE-2021-43572",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "CVE-2021-43572",
    "summary": "The verify function in the Stark Bank Python ECDSA library (aka starkbank-escada or ecdsa-python) before 2.0.1 fails to check that the signature is non-zero, which allows attackers to forge signatures on arbitrary messages.",
    "evidence": "osv:CVE-2021-43572",
    "products": [],
    "severity": "critical",
    "structured": {
      "id": "CVE-2021-43572",
      "aliases": [
        "CVE-2021-43572",
        "GHSA-92vm-mxjf-jqf3",
        "PYSEC-2021-426"
      ],
      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H"
        }
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://github.com/starkbank/ecdsa-python",
              "type": "GIT",
              "events": [
                {
                  "introduced": "0"
                },
                {
                  "fixed": "cb6d807a697d952916a0c46ce05ddd4d78718ca7"
                },
                {
                  "fixed": "d136170666e9510eb63c2572551805807bd4c17f"
                }
              ],
              "database_specific": {
                "extracted_events": [
                  {
                    "cpe": "cpe:2.3:a:starkbank:ecdsa-python:*:*:*:*:*:*:*:*",
                    "range": [
                      {
                        "introduced": "0"
                      },
                      {
                        "fixed": "2.0.1"
                      }
                    ],
                    "source": "CPE_RANGE"
                  },
                  {
                    "range": [
                      {
                        "fixed": "d136170666e9510eb63c2572551805807bd4c17f"
                      }
                    ],
                    "source": "REFERENCES_COMMIT"
                  },
                  {
                    "range": [
                      {
                        "fixed": "cb6d807a697d952916a0c46ce05ddd4d78718ca7"
                      }
                    ],
                    "source": "REFERENCES_TAG",
                    "original_tag": "v2.0.1"
                  }
                ]
              }
            }
          ],
          "versions": [
            "v2.0.0",
            "v1.1.1",
            "v1.1.0",
            "v1.0.0",
            "v0.1.9",
            "v0.1.8",
            "v0.1.7",
            "v0.1.4",
            "v0.1.3",
            "v0.1.2",
            "v0.1.1",
            "v0.1.0",
            "v0.1"
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2021-43572.json"
          }
        }
      ],
      "modified": "2026-10-20T10:55:02.887838765Z",
      "provider": "osv",
      "references": [
        "https://github.com/starkbank/ecdsa-python/releases/tag/v2.0.1",
        "https://github.com/starkbank/ecdsa-python/commit/d136170666e9510eb63c2572551805807bd4c17f",
        "https://research.nccgroup.com/2021/11/08/technical-advisory-arbitrary-signature-forgery-in-stark-bank-ecdsa-libraries/"
      ],
      "provider_metadata": {}
    },
    "related_cves": [
      {
        "value": "CVE-2021-43572",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 386771,
  "published_at": "2021-11-09T22:15:07.727+00:00"
}