GHSA-fv66-9v8q-g76r is a critical-severity (CVSS 10) Deserialization of Untrusted Data vulnerability in react-server-dom-webpack. 116 public exploit references exist, so weaponization risk is real. O3 Security confirms whether GHSA-fv66-9v8q-g76r is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
React Server Components are Vulnerable to RCE
Exploitation Status
Actively exploited in the wild
- CISA’s SSVC triage classifies this CVE as under active exploitation.
- 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’s SSVC triage for GHSA-fv66-9v8q-g76r.
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-fv66-9v8q-g76r 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-server-dom-webpacknpmDescription
Impact
There is an unauthenticated remote code execution vulnerability in React Server Components.
We recommend upgrading immediately.
The vulnerability is present in versions 19.0.0, 19.1.0, 19.1.1, and 19.2.0 of:
Patches
A fix was introduced in versions 19.0.1, 19.1.2, and 19.2.1. If you are using any of the above packages please upgrade to any of the fixed versions immediately.
If your app’s React code does not use a server, your app is not affected by this vulnerability. If your app does not use a framework, bundler, or bundler plugin that supports React Server Components, your app is not affected by this vulnerability.
References
See the blog post for more information and upgrade instructions.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | react-server-dom-webpack | ≥ 19.0.0&&< 19.0.1 | 19.0.1 |
| 📦npm | react-server-dom-webpack | ≥ 19.1.0&&< 19.1.2 | 19.1.2 |
| 📦npm | react-server-dom-webpack | ≥ 19.2.0&&< 19.2.1 | 19.2.1 |
| 📦npm | react-server-dom-turbopack | ≥ 19.0.0&&< 19.0.1 | 19.0.1 |
| 📦npm | react-server-dom-turbopack | ≥ 19.1.0&&< 19.1.2 | 19.1.2 |
| 📦npm | react-server-dom-turbopack | ≥ 19.2.0&&< 19.2.1 | 19.2.1 |
Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.
React Server 19.2.0 - Remote Code Execution
by danieljavanrad · Apr 9, 2026
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for react-server-dom-webpack. 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-server-dom-webpack to 19.0.1 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-fv66-9v8q-g76r 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-fv66-9v8q-g76r 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-fv66-9v8q-g76r. 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-fv66-9v8q-g76r in your dependencies?
O3 detects GHSA-fv66-9v8q-g76r across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.