GHSA-mh6f-8j2x-4483
CRITICALGHSA-mh6f-8j2x-4483 is a critical-severity (CVSS 9.8) vulnerability in event-stream. O3 Security confirms whether GHSA-mh6f-8j2x-4483 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Critical severity vulnerability that affects event-stream and flatmap-stream
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.
event-streamnpmflatmap-streamnpmDescription
The NPM package flatmap-stream is considered malicious. A malicious actor added this package as a dependency to the NPM event-stream package in version 3.3.6. Users of event-stream are encouraged to downgrade to the last non-malicious version, 3.3.4, or upgrade to the latest 4.x version.
Users of flatmap-stream are encouraged to remove the dependency entirely.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | event-stream | ≥ 3.3.6&&< 4.0.0 | 4.0.0 |
| 📦npm | flatmap-stream | all versions | No fix |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for event-stream. 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.
Fix
Update event-stream to 4.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-mh6f-8j2x-4483 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 pinpoints whether GHSA-mh6f-8j2x-4483 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-mh6f-8j2x-4483. 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-mh6f-8j2x-4483 in your dependencies?
O3 detects GHSA-mh6f-8j2x-4483 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.