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CRITICAL severity

GHSA-q9q6-f556-gpm7

CRITICAL

GHSA-q9q6-f556-gpm7 is a critical-severity (CVSS 9.8) CWE-347 vulnerability in starkbank-ecdsa. 1 public exploit reference exists, so weaponization risk is real. O3 Security confirms whether GHSA-q9q6-f556-gpm7 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.

Improper Verification of Cryptographic Signature in starkbank-ecdsa

Also known asCVE-2021-43571
Published
Nov 10, 2021
Updated
Nov 8, 2023
Affected
1 pkg
Patched
1 / 1
Exploits
1 known
Exploitation data as of Aug 23, 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 CVEs59th percentile — riskier than 59% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

How urgent is this, really

GHSA-q9q6-f556-gpm7 plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.

Where this sits among everything scored

Of 365,017 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.

Real-World Exposure

1 pkg affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

29other npm packages depend on this — each one inherits the vulnerability until it's patched upstream
starkbank-ecdsanpm
461Kdownloads / week

Description

The verify function in the Stark Bank Node.js ECDSA library (ecdsa-node) 1.1.2 fails to check that the signature is non-zero, which allows attackers to forge signatures on arbitrary messages.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
📦npmstarkbank-ecdsaall versions1.1.3
Exploits & PoCs
1

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

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for starkbank-ecdsa. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.

  2. Fix

    Update starkbank-ecdsa to 1.1.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-q9q6-f556-gpm7 is resolved across your whole dependency graph.

  3. 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.

  4. How O3 protects you

    O3 pinpoints whether GHSA-q9q6-f556-gpm7 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Tailored to GHSA-q9q6-f556-gpm7. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

The verify function in the Stark Bank Node.js ECDSA library (ecdsa-node) 1.1.2 fails to check that the signature is non-zero, which allows attackers to forge signatures on arbitrary messages.
O3 Security · Impact-Aware SCA

Is GHSA-q9q6-f556-gpm7 in your dependencies?

O3 detects GHSA-q9q6-f556-gpm7 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

GHSA-q9q6-f556-gpm7: starkbank-ecdsa… | O3 Security