React2Shell CVE-2025-55182 (CVSS 10, unauthenticated RCE in React Server Components / Next.js App Router, CISA KEV): which react-server-dom and Next.js versions are fixed?

Applies to: react-server-dom-webpack/parcel/turbopack 19.0.0, 19.1.0-19.1.1, 19.2.0; Next.js 15.x/16.x App Router before 15.0.5, 15.1.9, 15.2.6, 15.3.6, 15.4.8, 15.5.7, 16.0.7

How it was checked: Compiled on 2026-10-28 from Help Net Security, Datadog Security Labs and JFrog; not reproduced by Exuvia.

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Fix

What it is: CVE-2025-55182, nicknamed React2Shell, is a flaw in how React Server Components decode requests in the 'Flight' protocol. An unauthenticated attacker can send a crafted request to a server that runs React Server Components and execute code on it. It was disclosed in early December 2025, exploited within days, and added to CISA's Known Exploited Vulnerabilities catalog on December 5, 2025. Next.js tracked its downstream exposure as CVE-2025-66478. Frameworks that bundle the affected packages (Next.js App Router, React Router RSC, Waku, Vite and Parcel RSC plugins, RedwoodSDK) were affected. Am I affected: - Your app uses React Server Components with react-server-dom-webpack, react-server-dom-parcel or react-server-dom-turbopack 19.0.0, 19.1.0, 19.1.1 or 19.2.0 (check npm ls react-server-dom-webpack and the others), or Next.js 15.x / 16.x App Router releases before the fixed ones below. Next.js Pages Router-only apps and client-only React apps don't use the vulnerable server code. Fix: 1. Upgrade the react-server-dom-* package to 19.0.1, 19.1.2 or 19.2.1 or later (matching your React minor). 2. Next.js: upgrade to 15.0.5, 15.1.9, 15.2.6, 15.3.6, 15.4.8, 15.5.7 or 16.0.7 or later on your line (later security releases also fixed follow-up RSC bugs, so take the newest patch of your line). Rebuild and redeploy, including container images. 3. WAF rules from cloud providers can reduce exposure while you upgrade, but they are not a substitute for patching. After (exploitation was widespread soon after disclosure): - Look for unusual child processes of the Node.js server, new files, cryptominers and outbound connections since early December 2025. - If found, treat the host as compromised and rotate secrets available to the app: environment variables, database credentials, cloud keys and API tokens. Sources: https://www.helpnetsecurity.com/2025/12/04/react-node-js-vulnerability-cve-2025-55182/ https://securitylabs.datadoghq.com/articles/cve-2025-55182-react2shell-remote-code-execution-react-server-components/ https://jfrog.com/blog/2025-55182-and-2025-66478-react2shell-all-you-need-to-know

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