{"id":"CVE-2021-43572","aliases":["EUVD-2021-0251","GHSA-92vm-mxjf-jqf3","PYSEC-2021-426"],"status":"published","title":"Improper Verification of Cryptographic Signature in starkbank-ecdsa","description":"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.","severity":{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"primary","from":"nvd"},"epss":{"day":"2026-11-09","score":0.01248,"percentile":0.69557,"model":"v2026.06.15"},"facts":{"in_kev":false,"known_exploited":false,"public_exploit":false,"fix_available":true},"cwes":["CWE-347"],"published":"2021-11-09T21:05:20Z","modified":"2026-10-20T10:55:02Z","fixes":[{"ecosystem":"PyPI","package":"starkbank-ecdsa","fixed_in":["2.0.1"],"sources":["ghsa","osv"]}],"affected":[{"source":"ghsa","ecosystem":"PyPI","package":"starkbank-ecdsa","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.1"}]}]},{"source":"osv","ecosystem":"PyPI","package":"starkbank-ecdsa","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.1"}]}],"versions":["0.1","0.1.1","0.1.2","0.1.3","0.1.4","0.1.5","0.1.6","0.1.7","0.1.8","0.1.9","1.0.0","1.1.0","1.1.1","2.0.0"]},{"source":"osv","ecosystem":"PyPI","package":"starkbank-ecdsa","ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"0"},{"fixed":"2.0.1"}]}],"versions":["0.1","0.1.1","0.1.2","0.1.3","0.1.4","0.1.5","0.1.6","0.1.7","0.1.8","0.1.9","1.0.0","1.1.0","1.1.1","2.0.0"]}],"products":[{"vendor":"starkbank","product":"ecdsa-python"}],"references":[{"url":"https://research.nccgroup.com/2021/11/08/technical-advisory-arbitrary-signature-forgery-in-stark-bank-ecdsa-libraries/","tags":["x_refsource_MISC","x_transferred","Exploit","Third Party Advisory","evidence","advisory"]},{"url":"https://github.com/starkbank/ecdsa-python/releases/tag/v2.0.1","tags":["x_refsource_MISC","x_transferred","Release Notes","Third Party Advisory","advisory","web"]},{"url":"https://github.com/starkbank/ecdsa-python/commit/d136170666e9510eb63c2572551805807bd4c17f","tags":["x_refsource_MISC","x_transferred","Patch","Third Party Advisory","fix","web"]},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2021-43572","tags":["advisory"]},{"url":"https://github.com/pypa/advisory-database/tree/main/vulns/starkbank-ecdsa/PYSEC-2021-426.yaml","tags":["web"]},{"url":"https://research.nccgroup.com/2021/11/08/technical-advisory-arbitrary-signature-forgery-in-stark-bank-ecdsa-libraries","tags":["web"]},{"url":"https://github.com/advisories/GHSA-92vm-mxjf-jqf3","tags":["advisory"]},{"url":"https://github.com/starkbank/ecdsa-python","tags":["package"]}],"sources":{"cve":[{"id":"CVE-2021-43572","description":"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.","status":"published","published":"2021-11-09T21:05:20Z","modified":"2024-08-04T04:03:08.126Z","updated_at":"2026-11-02T14:32:56.689433Z"}],"euvd":[{"id":"EUVD-2021-0251","description":"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.","status":"published","published":"2021-11-09T21:05:20Z","modified":"2024-08-04T04:03:08Z","updated_at":"2026-11-03T03:24:13.772922Z"}],"ghsa":[{"id":"GHSA-92vm-mxjf-jqf3","title":"Improper Verification of Cryptographic Signature in starkbank-ecdsa","description":"The `verify` function in the Stark Bank Python ECDSA library (starkbank-ecdsa) 2.0.0 fails to check that the signature is non-zero, which allows attackers to forge signatures on arbitrary messages.","status":"published","published":"2021-11-10T20:41:39Z","modified":"2024-10-25T14:49:42Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-347"],"updated_at":"2026-11-02T14:38:13.09489Z"}],"nvd":[{"id":"CVE-2021-43572","description":"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.","status":"published","published":"2021-11-09T22:15:07.727Z","modified":"2026-06-17T04:11:09.49Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical","assessor":"primary"},{"version":"2.0","score":7.5,"vector":"AV:N/AC:L/Au:N/C:P/I:P/A:P","level":"high","assessor":"primary"}],"cwes":["CWE-347"],"updated_at":"2026-11-02T14:07:00.984108Z"}],"osv":[{"id":"CVE-2021-43572","description":"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.","status":"published","published":"2021-11-09T22:15:07.727Z","modified":"2026-10-20T10:55:02.887838765Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"updated_at":"2026-11-02T15:44:21.877444Z"},{"id":"GHSA-92vm-mxjf-jqf3","title":"Improper Verification of Cryptographic Signature in starkbank-ecdsa","description":"The `verify` function in the Stark Bank Python ECDSA library (starkbank-ecdsa) 2.0.0 fails to check that the signature is non-zero, which allows attackers to forge signatures on arbitrary messages.","status":"published","published":"2021-11-10T20:41:39Z","modified":"2024-10-25T15:01:08.810162Z","cvss":[{"version":"3.1","score":9.8,"vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","level":"critical"}],"cwes":["CWE-347"],"updated_at":"2026-11-02T15:46:43.123867Z"},{"id":"PYSEC-2021-426","description":"The verify function in the Stark Bank Python ECDSA library (ecdsa-python) 2.0.0 fails to check that the signature is non-zero, which allows attackers to forge signatures on arbitrary messages.","status":"published","published":"2021-11-09T22:15:00Z","modified":"2023-11-08T04:07:10.830168Z","updated_at":"2026-11-02T15:52:53.119977Z"}]}}