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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.
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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.
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.
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.
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.
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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Multiple vulnerabilities have been identified in React Server Components (RSC), specifically CVE-2025-55183, CVE-2025-55184, and CVE-2025-67779, affecting several versions of `react-server-dom-webpack`, `react-server-dom-parcel`, and `react-server-dom-turbopack`. These vulnerabilities, discovered following the React2Shell incident, include a high-severity denial-of-service (DoS) flaw (CVE-2025-55184) caused by unsafe deserialization of structured input in the RSC Flight protocol, which can be exploited by sending specially crafted requests that trigger infinite loops or event-loop lockups on the server. The vulnerabilities also raise concerns about potential source code exposure and highlight the risk of residual flaws being discovered after major disclosures. The React Foundation has issued advisories and patches for affected versions, and the Canadian Centre for Cyber Security has urged administrators to update impacted libraries and frameworks, including popular tools such as Next.js, Vite RSC plugin, Parcel RSC plugin, React Router RSC preview, RedwoodSDK, and Waku. No public exploits are currently available, but the vulnerabilities have a higher-than-average likelihood of exploitation, emphasizing the importance of prompt remediation and ongoing vigilance for follow-on issues after initial vulnerability disclosures.
Jun 29, 2026
A critical remote code execution vulnerability in React Server Components-related packages is affecting widely used parts of the React ecosystem, including deployments tied to **Next.js**, **React Router**, **Expo**, **Redwood SDK**, **Waku**, and `@vitejs/plugin-rsc`. The flaw allows an unauthenticated attacker to execute arbitrary code on a vulnerable system through an HTTP request. Affected versions include `19.0`, `19.1.0`, `19.1.1`, and `19.2.0` of `react-server-dom-webpack`, `react-server-dom-parcel`, and `react-server-dom-turbopack`, while patched releases are `19.0.1`, `19.1.2`, and `19.2.1`. Authorities warned that exploitation is already active in Finland and that public exploit methods are available, increasing the likelihood of rapid opportunistic attacks against exposed applications. Officials said attackers may use the vulnerability not only for visible abuse such as cryptomining but also to establish persistent access, and urged organizations to patch immediately and assess internet-exposed systems for signs of compromise.
Jun 29, 2026
React maintainers have released patches addressing two newly discovered vulnerabilities that could allow attackers to crash servers via denial-of-service (DoS) attacks and potentially disclose sensitive source code. These flaws, which follow closely after the React2Shell incident, have raised concerns about the security of applications built with React, especially those exposed to untrusted input or running in server-side environments. The vulnerabilities are tracked as CVE-2025-55183, CVE-2025-55184, and CVE-2025-67779, and security researchers urge immediate attention and patching to mitigate exploitation risks. Security experts highlight that the vulnerabilities could be exploited to disrupt services or leak proprietary code, posing significant risks to organizations relying on React for web application development. The issues have been acknowledged by both the React development team and independent security researchers, with proof-of-concept details and technical advisories made available to the public. Organizations are advised to review their deployments and apply the latest security updates to prevent potential attacks leveraging these flaws.
Jun 29, 2026