{"cve":"CVE-2021-43572","nvd":{"published":"2021-11-09T22:15:07.727","modified":"2026-06-17T04:11:09.490","status":"Modified","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H","score":9.8},"cwes":["CWE-347"],"references":["https://github.com/starkbank/ecdsa-python/commit/d136170666e9510eb63c2572551805807bd4c17f","https://github.com/starkbank/ecdsa-python/releases/tag/v2.0.1","https://research.nccgroup.com/2021/11/08/technical-advisory-arbitrary-signature-forgery-in-stark-bank-ecdsa-libraries/","https://github.com/starkbank/ecdsa-python/commit/d136170666e9510eb63c2572551805807bd4c17f","https://github.com/starkbank/ecdsa-python/releases/tag/v2.0.1"],"products":["starkbank:ecdsa-python"],"source":"nvd","synced_at":"2026-10-19T21:24:39.218183596+00:00"},"epss":{"cve":"CVE-2021-43572","score":0.01248,"percentile":0.69364,"date":"2026-10-31"},"kev":null,"osv":[{"id":"GHSA-92vm-mxjf-jqf3","url":"https://osv.dev/vulnerability/GHSA-92vm-mxjf-jqf3","summary":"Improper Verification of Cryptographic Signature in starkbank-ecdsa","modified":"2024-10-25T15:01:08.810162Z","packages":[{"ecosystem":"PyPI","name":"starkbank-ecdsa","purl":"pkg:pypi/starkbank-ecdsa","ranges":["<2.0.1"],"fixed":["2.0.1"]}]},{"id":"PYSEC-2021-426","url":"https://osv.dev/vulnerability/PYSEC-2021-426","summary":"","modified":"2023-11-08T04:07:10.830168Z","packages":[{"ecosystem":"PyPI","name":"starkbank-ecdsa","purl":"pkg:pypi/starkbank-ecdsa","ranges":["<2.0.1"],"fixed":["2.0.1"]}]}],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}