Impact It is possible to bypass authorization checks within a Next.js application, if the authorization check occurs in middleware.
Patches For Next.js 15.x, this issue is fixed in 15.2.3 For Next.js 14.x, this issue is fixed in 14.2.25 For Next.js 13.x, this issue is fixed in 13.5.9 For Next.js 12.x, this issue is fixed in 12.3.5 For Next.js 11.x, consult the below workaround.
Note: Next.js deployments hosted on Vercel are automatically protected against this vulnerability.
Workaround If patching to a safe version is infeasible, it is recommend that you prevent external user requests which contain the x-middleware-subrequest header from reaching your Next.js application.
Credits
- Allam Rachid (zhero;) - Allam Yasser (inzo)
Impact
An attacker-controlled, allow-listed remote URL can lead to server-side request forgery (e.g. to private IPs) during Image Optimization.
Workaround
Audit allow-listed remote URLs in images.remotePatterns (see https://nextjs.org/docs/app/getting-started/images#remote-images) for hosts that may not be trusted with their DNS entries. If no images.remotePatterns are configured, your app is not affected.
Next.js is a React framework that can provide building blocks to create web applications. A Server-Side Request Forgery (SSRF) vulnerability was identified in Next.js Server Actions. If the Host header is modified, and the below conditions are also met, an attacker may be able to make requests that appear to be originating from the Next.js application server itself. The required conditions are 1) Next.js is running in a self-hosted manner; 2) the Next.js application makes use of Server Actions; and 3) the Server Action performs a redirect to a relative path which starts with a /. This vulnerability was fixed in Next.js 14.1.1.
Next.js is a React framework for building full-stack web applications. From to before 15.5.16 and 16.2.5, applications using Partial Prerendering through the Cache Components feature can be vulnerable to connection exhaustion through crafted POST requests to a server action. In affected configurations, a malicious request can trigger a request-body handling deadlock that leaves connections open for an extended period, consuming file descriptors and server capacity until legitimate users are denied service. This vulnerability is fixed in 15.5.16 and 16.2.5.
Next.js is a React framework for building full-stack web applications. From 13.4.13 to before 15.5.16 and 16.2.5, self-hosted applications using the built-in Node.js server can be vulnerable to server-side request forgery through crafted WebSocket upgrade requests. An attacker can cause the server to proxy requests to arbitrary internal or external destinations, which may expose internal services or cloud metadata endpoints. Vercel-hosted deployments are not affected. This vulnerability is fixed in 15.5.16 and 16.2.5.
Next.js is a React framework for building full-stack web applications. From 15.4.0 to before 15.5.16 and 16.2.5, applications that rely on middleware to protect dynamic routes can be vulnerable to authorization bypass. In affected deployments, specially crafted query parameters can alter the dynamic route value seen by the page while leaving the visible path unchanged, which can allow protected content to be rendered without passing the expected middleware check. This vulnerability is fixed in 15.5.16 and 16.2.5.
Next.js is a React framework for building full-stack web applications. From 15.2.0 to before 15.5.16 and 16.2.5, App Router applications that rely on middleware or proxy-based checks for authorization can allow unauthorized access through transport-specific route variants used for segment prefetching. In affected configurations, specially crafted .rsc and segment-prefetch URLs can resolve to the same page without being matched by the intended middleware rule, which can allow protected content to be reached without the expected authorization check. This vulnerability is fixed in 15.5.16 and 16.2.5.
Next.js applications that use a root-level catch-all page together with statically generated or Incremental Static Regeneration routes can have their shared response cache poisoned by a single unauthenticated crafted request.
Next.js is a React framework for building full-stack web applications. From 16.3.0 until 16.3.8, pending use cache fills for the same key are shared without separating Draft Mode requests from regular requests. An overlapping regular request can receive unauthenticated unpublished content from an editor's Draft Mode fill, while an overlapping Draft Mode request can receive published content from a regular fill. When the regular request prerenders a page, the draft-dependent content can persist in the generated page and be served to later visitors until revalidation. Sites are affected when Cache Components or experimental.useCache is enabled and cached functions return draft-dependent content. This issue is fixed in version 16.3.8.
Next.js is a React framework for building full-stack web applications. From 15.0.0 until 15.5.27 and 16.3.8, self-hosted applications using the Pages Router with statically generated or Incremental Static Regeneration pages can key a response cache entry without sufficiently binding it to the source route. A request can replace one page's cache entry with content from a different route, causing the affected page to serve incorrect content to every visitor until revalidation. Applications deployed on Vercel are not affected. This issue is fixed in versions 15.5.27 and 16.3.8.
Next.js is a React framework for building full-stack web applications. From 16.0.0 until 16.3.8, the next dev development server exposes a Model Context Protocol endpoint without reliably restricting cross-site requests. A malicious website visited by a developer can reach the endpoint and read the project's disk location, source code snippets from error reports, route inventory, and development logs. Production deployments do not serve this endpoint. This issue is fixed in version 16.3.8.
End of life: 10/26/2025, Latest version: 14.2.35
End of life: 10/26/2025, Latest version: 14.2.35
End of life: 10/21/2026, Latest version: 15.5.28
End of life: 10/21/2026, Latest version: 15.5.28
A vulnerable OG image endpoint could potentially allow an unauthenticated attacker to achieve remote code execution. Affected: Next.js 16.2.0–16.3.5 Fixed: Next.js 16.3.6 / Satori 0.33.5 Edge runtime or setups without sharp are reportedly not affected. If you’re running an affected version, update now.