CVE-2026-23870
HIGHCVE-2026-23870 is a high-severity (CVSS 7.5) vulnerability in react-server-dom-parcel. O3 Security confirms whether CVE-2026-23870 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Facebook React has a Denial of Service Vulnerability in React Server Components
Real-World Exposure
How broadly this vulnerability is actually deployed: weekly install volume shows current usage, a proxy for how much of the ecosystem is exposed.
react-server-dom-parcelnpmreact-server-dom-turbopacknpmreact-server-dom-webpacknpmDescription
A denial of service vulnerability could be triggered by sending specially crafted HTTP requests to server function endpoints, this could lead to server crashes, out-of-memory exceptions or excessive CPU usage; affecting the following packages: react-server-dom-webpack, react-server-dom-parcel, react-server-dom-turbopack (versions 19.0.0 through 19.0.5, 19.1.0 through 19.1.6, and 19.2.0 through 19.2.5).
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| 📦npm | react-server-dom-parcel | ≥ 19.0.0&&< 19.0.6 | 19.0.6 |
| 📦npm | react-server-dom-turbopack | ≥ 19.0.0&&< 19.0.6 | 19.0.6 |
| 📦npm | react-server-dom-webpack | ≥ 19.0.0&&< 19.0.6 | 19.0.6 |
| 📦npm | react-server-dom-parcel | ≥ 19.1.0&&< 19.1.7 | 19.1.7 |
| 📦npm | react-server-dom-turbopack | ≥ 19.1.0&&< 19.1.7 | 19.1.7 |
| 📦npm | react-server-dom-webpack | ≥ 19.1.0&&< 19.1.7 | 19.1.7 |
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-parcel. 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-parcel to 19.0.6 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-23870 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 CVE-2026-23870 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 CVE-2026-23870. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-23870 in your dependencies?
O3 detects CVE-2026-23870 across npm dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.