CVE-2021-43572
Improper Verification of Cryptographic Signature in starkbank-ecdsa
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.
Attack profile
How easy it is to exploit
- Attack vector
- Network
- Complexity
- Low
- Privileges needed
- None
- User interaction
- None
What an attacker can affect
- Confidentiality
- High
- Integrity
- High
- Availability
- High
Exploit likelihood
What each source reports
NVD Score used
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.
- Record
CVE-2021-43572- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - CVSS 2.0
- 7.5 High
AV:N/AC:L/Au:N/C:P/I:P/A:P - Weakness
- CWE-347
- Updated
- 2026-11-02
CVE List No score
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.
- Record
CVE-2021-43572- Updated
- 2026-11-02
EUVDEUVD-2021-0251 No score
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.
- Record
EUVD-2021-0251- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-92vm-mxjf-jqf3
Improper Verification of Cryptographic Signature in starkbank-ecdsa
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.
- Record
GHSA-92vm-mxjf-jqf3- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-347
- Updated
- 2026-11-02
OSV
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.
- Record
CVE-2021-43572- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Updated
- 2026-11-02
OSVGHSA-92vm-mxjf-jqf3
Improper Verification of Cryptographic Signature in starkbank-ecdsa
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.
- Record
GHSA-92vm-mxjf-jqf3- CVSS 3.1
- 9.8 Critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - Weakness
- CWE-347
- Updated
- 2026-11-02
OSVPYSEC-2021-426 No score
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.
- Record
PYSEC-2021-426- Updated
- 2026-11-02
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
starkbank-ecdsaPyPI |
before 2.0.1 | 2.0.1 |
starkbank-ecdsaPyPI |
before 2.0.1, plus listed versions 0.10.1.10.1.20.1.30.1.4 Show 9 moreShow less0.1.50.1.60.1.70.1.80.1.91.0.01.1.01.1.12.0.0 |
2.0.1 |
History
| Recorded | Changed | Sources |
|---|---|---|
| aliases | EUVD | |
| first indexed | CVE List, GitHub Advisories, NVD, OSV |
Dates are when Every CVE recorded each change. Upstream dates may differ.
In short
CVE-2021-43572 is a critical vulnerability (CVSS 9.8) in Starkbank Ecdsa-python, published November 9, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.25%, the 69th percentile. Fixed in starkbank-ecdsa 2.0.1.
References
research.nccgroup.com/2021/11/08/technical-advisory-arbitrary-signature-forgery-in-stark-bank-ecdsa-libraries
github.com/starkbank/ecdsa-python/releases/tag/v2.0.1
nvd.nist.gov/vuln/detail/CVE-2021-43572