How severe is CVE-2021-43570?

CVE-2021-43570 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which packages are affected by CVE-2021-43570?

CVE-2021-43570 affects the following packages: com.starkbank.ellipticcurve:starkbank-ecdsa (Maven). Ecosystems affected: Maven.

How do I fix CVE-2021-43570?

Update com.starkbank.ellipticcurve:starkbank-ecdsa to 1.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-43570 is resolved across your whole dependency graph.

How do I detect CVE-2021-43570 in my Maven dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.starkbank.ellipticcurve:starkbank-ecdsa, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate CVE-2021-43570 if there is no patch (or I can't update yet)?

If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Is CVE-2021-43570 actively exploited in the wild?

Yes. There are 1 known exploit references for CVE-2021-43570, including 1 in-the-wild exploitation observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2021-43570?

CVE-2021-43570 has an EPSS (Exploit Prediction Scoring System) score of 1.0%, placing it in the 63th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is CVE-2021-43570?

CVE-2021-43570 is classified as CWE-347 (CWE-347). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation.

When was CVE-2021-43570 published, and has it been updated?

CVE-2021-43570 was published on November 9, 2021 and was last updated on July 9, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

☕

☕ Maven

Not in CISA KEV

CRITICAL severity

CVE-2021-43570 — starkbank-ecdsa

CRITICALFix: starkbank/ecdsa-java#16

CVE-2021-43570 is a critical-severity (CVSS 9.8) CWE-347 vulnerability in com.starkbank.ellipticcurve:starkbank-ecdsa. 1 public exploit reference exists, so weaponization risk is real. A fix is available for com.starkbank.ellipticcurve:starkbank-ecdsa — see the affected versions and patch details below.

Improper Verification of Cryptographic Signature in starkbank-ecdsa

Also known asGHSA-r28h-x6hv-2fq3

Published

Nov 9, 2021

Updated

Jul 9, 2026

Affected

1 pkg

Patched

1 / 1

Exploits

1 known

Exploitation data as of Oct 13, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

EPSS Exploitation Probability

via FIRST.org ↗

1.0%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs63th percentile — riskier than 63% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2021-43570 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 386,684 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

1 pkg affected

☕com.starkbank.ellipticcurve:starkbank-ecdsa

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects Maven packages — download data is not available via public APIs for these ecosystems.

Description

The verify function in the Stark Bank Java ECDSA library (ecdsa-java) 1.0.0 fails to check that the signature is non-zero, which allows attackers to forge signatures on arbitrary messages.

Affected Packages

1 total 1 fixed

Ecosystem	Package	Vulnerable range	Fix
☕Maven	`com.starkbank.ellipticcurve:starkbank-ecdsa`	all versions	1.0.1`com.starkbank.ellipticcurve:starkbank-ecdsa:1.0.1`

Affected Products

1 product · 1 configurations

Application

ecdsa-javastarkbank

1 version

1.0.0

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

The verify function in the Stark Bank Java ECDSA library (ecdsa-java) 1.…

research.nccgroup.comNVDNov 2021

Detection & mitigation playbook

Open-source dependency

Detect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for com.starkbank.ellipticcurve:starkbank-ecdsa, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update com.starkbank.ellipticcurve:starkbank-ecdsa to 1.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2021-43570 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

Frequently Asked Questions

The verify function in the Stark Bank Java ECDSA library (ecdsa-java) 1.0.0 fails to check that the signature is non-zero, which allows attackers to forge signatures on arbitrary messages.

O3 Security · Impact-Aware SCA

Is CVE-2021-43570 in your dependencies?

Find it across Maven, including transitive dependencies.

Scan my dependencies How O3 SCA works

CVSS Score

9.8/10CVSS v3 base

Vector breakdown

Attack Vector

Network

Attack Complexity

Low

Privileges Required

None

User Interaction

None

Scope

Unchanged

Confidentiality

High

Integrity

High

Availability

High

Raw vector

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

CWE Classification

CWE-347CWE-347

Weaponization

No known public exploit tooling found.

Timeline

Disclosed

Nov 9, 2021

First exploit

Nov 12, 2021

3 days after disclosure — rapid exploitation

Last updated

Jul 9, 2026

Identifiers

CVE-2021-43570

GHSA-r28h-x6hv-2fq3

References

Advisorygithub.com Advisorynvd.nist.gov Webgithub.com Webgithub.com Webresearch.nccgroup.com Packagegithub.com Evidenceresearch.nccgroup.com

Related vulnerabilities

This CVE is critical severity; 1 of 8 other CVEs with CWE-347 is rated as high or higher (top: critical).

CVE-2026-59163CVE-2026-86038CVE-2026-86080GHSA-73p9-6hrp-8qhrCVE-2026-54736CVE-2026-54155GHSA-fhgh-wq4q-r37xCVE-2026-53501Browse all CWE-347

Provenance

Sources

OSV.devNVDFIRST.org (EPSS)

Last verifiedJul 9, 2026

CVE-2021-43570 — starkbank-ecdsa

EPSS Exploitation Probability

How urgent is this, really

Where this sits among everything scored

Real-World Exposure

Description

Affected Packages

Affected Products

Detection & mitigation playbook

Detect

Fix

Workarounds

Frequently Asked Questions

Is CVE-2021-43570 in your dependencies?