GHSA-5gc4-cx9x-9c43 is a critical-severity (CVSS 9) Code Injection vulnerability in metacalc. 1 public exploit reference exists, so weaponization risk is real. A fix is available for metacalc — see the affected versions and patch details below.
Code Injection in metacalc
EPSS Exploitation Probability
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-5gc4-cx9x-9c43 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 379,145 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
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.
metacalcnpmDescription
The package metacalc before 0.0.2 are vulnerable to Arbitrary Code Execution when it exposes JavaScript's Math class to the v8 context. As the Math class is exposed to user-land, it can be used to get access to JavaScript's Function constructor.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | metacalc | all versions | 0.0.2npm install metacalc@0.0.2 |
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 dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for metacalc, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
Fix
Update metacalc to 0.0.2 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-5gc4-cx9x-9c43 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.
How O3 protects you
O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-5gc4-cx9x-9c43 can be triaged on real exposure rather than presence alone.
Tailored to GHSA-5gc4-cx9x-9c43. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is GHSA-5gc4-cx9x-9c43 in your dependencies?
O3 Security finds GHSA-5gc4-cx9x-9c43 across npm dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.