CVE-2021-43569
Improper Verification of Cryptographic Signature in starkbank-ecdsa
The verify function in the Stark Bank .NET ECDSA library (ecdsa-dotnet) 1.3.1 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 .NET ECDSA library (ecdsa-dotnet) 1.3.1 fails to check that the signature is non-zero, which allows attackers to forge signatures on arbitrary messages.
- Record
CVE-2021-43569- 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 .NET ECDSA library (ecdsa-dotnet) 1.3.1 fails to check that the signature is non-zero, which allows attackers to forge signatures on arbitrary messages.
- Record
CVE-2021-43569- Updated
- 2026-11-02
EUVDEUVD-2021-2359 No score
The verify function in the Stark Bank .NET ECDSA library (ecdsa-dotnet) 1.3.1 fails to check that the signature is non-zero, which allows attackers to forge signatures on arbitrary messages.
- Record
EUVD-2021-2359- Updated
- 2026-11-03
GitHub AdvisoriesGHSA-j3jw-j2j8-2wv9
Improper Verification of Cryptographic Signature in starkbank-ecdsa
The verify function in the Stark Bank .NET ECDSA library (ecdsa-dotnet) 1.3.1 fails to check that the signature is non-zero, which allows attackers to forge signatures on arbitrary messages.
- Record
GHSA-j3jw-j2j8-2wv9- 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 .NET ECDSA library (ecdsa-dotnet) 1.3.1 fails to check that the signature is non-zero, which allows attackers to forge signatures on arbitrary messages.
- Record
CVE-2021-43569- 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-j3jw-j2j8-2wv9
Improper Verification of Cryptographic Signature in starkbank-ecdsa
The verify function in the Stark Bank .NET ECDSA library (ecdsa-dotnet) 1.3.1 fails to check that the signature is non-zero, which allows attackers to forge signatures on arbitrary messages.
- Record
GHSA-j3jw-j2j8-2wv9- 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
Affected products
Affected packages
| Package | Affected | Fixed |
|---|---|---|
starkbank-ecdsaNuGet |
before 1.3.2 | 1.3.2 |
starkbank-ecdsaNuGet |
before 1.3.2, plus listed versions 0.0.11.0.01.1.01.2.01.2.11.3.01.3.1 |
1.3.2 |
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-2021-43569 is a critical vulnerability (CVSS 9.8) in Starkbank Ecdsa-dotnet, published November 9, 2021. No source lists public exploit code. EPSS puts the chance of exploitation in the next 30 days at 1.06%, the 64th percentile. Fixed in starkbank-ecdsa 1.3.2.