CVE-2022-36046 in Next.js
Summary
by MITRE • 08/31/2022
Next.js is a React framework that can provide building blocks to create web applications. All of the following must be true to be affected by this CVE: Next.js version 12.2.3, Node.js version above v15.0.0 being used with strict `unhandledRejection` exiting AND using next start or a [custom server](https://nextjs.org/docs/advanced-features/custom-server). Deployments on Vercel ([vercel.com](https://vercel.com/)) are not affected along with similar environments where `next-server` isn't being shared across requests.
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Analysis
by VulDB Data Team • 09/01/2022
This vulnerability in Next.js version 12.2.3 represents a critical runtime error handling flaw that specifically manifests when certain environmental conditions are met. The issue occurs in environments where Node.js versions above v15.0.0 are configured with strict unhandledRejection exiting behavior combined with the use of next start command or custom server implementations. The vulnerability stems from how Next.js handles asynchronous error propagation within its server-side rendering pipeline, creating a scenario where unhandled promise rejections can cause application crashes and unexpected termination. This flaw is particularly dangerous because it can lead to complete service outages when legitimate errors occur during request processing, making it a significant concern for production deployments where reliability is paramount.
The technical root cause of CVE-2022-36046 lies in Next.js's improper handling of asynchronous operations within its server runtime environment. When strict unhandledRejection exiting is enabled, Node.js terminates the process immediately upon encountering an unhandled promise rejection, which can happen during various server-side operations including API route processing, data fetching, or static site generation tasks. The framework's internal error handling mechanisms fail to properly intercept and manage these specific error conditions, leading to process termination rather than graceful error recovery. This behavior aligns with CWE-703, which catalogs improper handling of exceptional conditions, and specifically demonstrates weaknesses in error propagation and recovery mechanisms within server-side applications.
The operational impact of this vulnerability extends beyond simple application crashes to potentially compromise entire deployment environments. When affected systems experience unhandled rejections, they can enter into continuous restart loops, causing denial of service conditions that affect all users accessing the application. The vulnerability particularly affects deployments using custom server configurations or the next start command because these execution paths bypass certain error handling safeguards present in default Next.js deployments. Organizations running on Vercel or similar platforms remain unaffected due to the isolated nature of their server environments where next-server instances are not shared across requests, illustrating how deployment architecture can significantly influence vulnerability exploitation. This scenario demonstrates ATT&CK technique T1499.004, which involves network disruption through service availability attacks, as the vulnerability can be leveraged to cause service unavailability through process termination.
Mitigation strategies for CVE-2022-36046 require immediate attention from system administrators and development teams. The most effective approach involves upgrading to Next.js versions that have patched this vulnerability, typically those released after the initial vulnerability disclosure. Organizations should also consider implementing custom error handling middleware that can catch and properly manage unhandled promise rejections before they reach the Node.js process level. Additionally, removing or modifying the strict unhandledRejection exiting behavior in affected environments can provide temporary relief while longer-term solutions are implemented. Security teams should monitor their deployments for signs of process termination or restart patterns that might indicate exploitation attempts, and implement proper logging to track error conditions that could lead to service disruption. The vulnerability highlights the importance of maintaining up-to-date frameworks and understanding how different deployment configurations can affect security posture, particularly in server-side rendering environments where error handling becomes critical for application stability.