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CVE-2021-43569

31
FAUCET Score

CVE-2021-43569 is a critical vulnerability in the Stark Bank .NET ECDSA library (ecdsa-dotnet) version 1.3.1, where the verify function fails to validate non-zero signatures, enabling attackers to forge signatures on arbitrary messages. This flaw carries a CVSS score of 9.8 (Critical), indicating an easily exploitable network-based attack with high impact on confidentiality, integrity, and availability. While there is no evidence of active exploitation or publicly available exploit code, the vulnerability has garnered significant community discussion, suggesting awareness among security researchers.

Impacted Technologies

VendorProductVersion(s)CPE
1.3.2CPE matchmatch criteria
cpe:2.3:a:starkbank:ecdsa-dotnet:1.3.2:*:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.02%
Probability of exploitation in next 30 days
EPSS Percentile
59.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-26
Model: v2026.06.15
This CVE's current EPSS score of 0.0102 is in the 45th percentile among its peer group of 36,835 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

No media coverage found for this CVE.

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Patch Available

Vendor Patches (1)

nugetpatch availablevia ghsa
Product: starkbank-ecdsaFixed in: 1.3.2

Vendor Advisories (1)

nugetGHSA-j3jw-j2j8-2wv9critical

Improper Verification of Cryptographic Signature in starkbank-ecdsa

Nov 10, 2021

References

github.com / starkbank/ecdsa-dotnet/releases/tag/v1.3.2
Third Party Advisory
research.nccgroup.com / 2021/11/08/technical-advisory-arbitrary-signature-forgery-in-stark-bank-ecdsa-libraries
ExploitThird Party Advisory