GHSA-399j-vxmf-hjvr is a critical-severity (CVSS 9.8) OS Command Injection vulnerability in @react-native-community/cli. It is in CISA's Known Exploited Vulnerabilities catalog (added 2026-02-05) — treat it as actively exploited and patch now. O3 Security confirms whether GHSA-399j-vxmf-hjvr is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
@react-native-community/cli has arbitrary OS command injection
Exploitation Status
Actively exploited in the wild
- Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2026-02-05. Federal agencies were required to remediate by 2026-02-26.
- CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
- A successful exploit gives an attacker total control of the affected component, not partial access.
Exploitation and automatability from CISA (KEV catalog and SSVC triage) for GHSA-399j-vxmf-hjvr.
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-399j-vxmf-hjvr plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE sits: patch-first territory.
Where this sits among everything scored
Of 0 CVEs with a current EPSS score, this one falls in the ≥ 90% 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.
@react-native-community/clinpmDescription
The Metro Development Server, which is opened by the React Native CLI, binds to external interfaces by default. The server exposes an endpoint that is vulnerable to OS command injection. This allows unauthenticated network attackers to send a POST request to the server and run arbitrary executables. On Windows, the attackers can also execute arbitrary shell commands with fully controlled arguments.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | @react-native-community/cli | ≥ 20.0.0-alpha.0&&< 20.0.0 | 20.0.0 |
| 📦npm | @react-native-community/cli | ≥ 19.0.0-alpha.0&&< 19.1.2 | 19.1.2 |
| 📦npm | @react-native-community/cli | ≥ 18.0.0&&< 18.0.1 | 18.0.1 |
| 📦npm | @react-native-community/cli-server-api | ≥ 20.0.0-alpha.0&&< 20.0.0 | 20.0.0 |
| 📦npm | @react-native-community/cli-server-api | ≥ 19.0.0-alpha.0&&< 19.1.2 | 19.1.2 |
| 📦npm | @react-native-community/cli-server-api | ≥ 18.0.0&&< 18.0.1 | 18.0.1 |
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 dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for @react-native-community/cli. 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 @react-native-community/cli to 20.0.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-399j-vxmf-hjvr 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-399j-vxmf-hjvr 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-399j-vxmf-hjvr. 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-399j-vxmf-hjvr in your dependencies?
O3 detects GHSA-399j-vxmf-hjvr across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.