A maximum severity vulnerability, dubbed 'React2Shell', in the React Server Components (RSC) 'Flight' protocol allows remote code execution without authentication in React and Next.js applications.
The security issue stems from insecure deserialization. It received a severity score of 10/10 and has been assigned the identifiers CVE-2025-55182 for React and CVE-2025-66478 (CVE rejected in the National Vulnerability Database) for Next.js.
Security researcher Lachlan Davidson discovered the flaw and reported it to React on November 29. He found that an attacker could achieve remote code execution (RCE) by sending a specially crafted HTTP request to React Server Function endpoints.
"Even if your app does not implement any React Server Function endpoints, it may still be vulnerable if your app supports React Server Components [RCS]," warns the security advisory from React.
The following packages in their default configuration are impacted:
react-server-dom-parcel
react-server-dom-turbopack
and react-server-dom-webpack
React is an open-source JavaScript library for building user interfaces. It's maintained by Meta and widely adopted by organizations of all sizes for front-end web development.
Next.js, maintained by Vercel, is a framework built on top of React that adds server-side rendering, routing, and API endpoints.
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