Denial-of-Service and Source Code Exposure Vulnerabilities in React Server Components
Security researchers have identified three new vulnerabilities in React Server Components (RSC) following the recent patch for the critical React2Shell exploit. These flaws include two high-severity Denial-of-Service (DoS) vulnerabilities (CVE-2025-55184 and CVE-2025-67779) and a medium-severity Source Code Exposure vulnerability (CVE-2025-55183). The DoS vulnerabilities allow attackers to send malicious HTTP requests to Server Function endpoints, triggering infinite loops that hang the server and exhaust CPU resources, effectively taking applications offline. The source code exposure flaw enables attackers to craft HTTP requests that can leak the source code of server functions, potentially exposing hardcoded secrets or sensitive logic, though runtime secrets remain protected.
The affected packages are react-server-dom-webpack, react-server-dom-parcel, and react-server-dom-turbopack, impacting React versions 19.0.0 through 19.2.2 and frameworks such as Next.js, Waku, and React Router. Initial patches released for these vulnerabilities were incomplete, necessitating immediate upgrades to versions 19.0.3, 19.1.4, and 19.2.3 to ensure full protection. The vulnerabilities were discovered by security researchers during attempts to bypass previous mitigations, highlighting the importance of rapid patch adoption and ongoing scrutiny of critical code paths after major disclosures. Users are strongly advised to update affected packages and monitor official channels for further security updates.
Timeline
Dec 18, 2025
Vercel deploys WAF protections for hosted projects
Vercel said it deployed WAF rules to help protect projects hosted on its platform from the React Server Components vulnerabilities affecting React 19 and Next.js. It emphasized that these protections are temporary and that customers still need to upgrade to patched React and Next.js versions.
Dec 11, 2025
Akamai deploys protections and publishes mitigation guidance
Akamai announced Adaptive Security Engine Rapid Rules and related detection and mitigation guidance for customers affected by CVE-2025-55183 and CVE-2025-55184. The company also provided asset-identification queries and recommended prompt vendor patching as the primary mitigation.
Dec 11, 2025
React discloses the new CVEs and releases patched versions
React publicly disclosed the new vulnerabilities on its blog and released fixes backported to versions 19.0.3, 19.1.4, and 19.2.3. The advisory warned that crafted HTTP requests could hang server processes or expose Server Function source code, and urged immediate upgrades.
Dec 11, 2025
Researchers identify new RSC DoS and source code exposure flaws
During follow-up security research on React2Shell, researchers Andrew MacPherson, RyotaK, and Shinsaku Nomura discovered additional React Server Components vulnerabilities: DoS issues CVE-2025-55184 and CVE-2025-67779, and source code exposure flaw CVE-2025-55183. The bugs affect react-server-dom-webpack, react-server-dom-parcel, and react-server-dom-turbopack across vulnerable React 19.x releases.
Dec 4, 2025
React2Shell RCE flaw is disclosed and patched incompletely
Before the newly disclosed issues, React patched the critical React Server Components remote code execution flaw CVE-2025-55182 ("React2Shell"). Subsequent research found the initial mitigations were incomplete, leaving room for bypasses and follow-on vulnerabilities.
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