CVE-2025-29927 PoC — Authorization Bypass in Next.js Middleware

Title:Authorization Bypass in Next.js Middleware (CVE-2025-29927)
Description:Next.js is a React framework for building full-stack web applications. Starting in version 1.11.4 and prior to versions 12.3.5, 13.5.9, 14.2.25, and 15.2.3, it is possible to bypass authorization checks within a Next.js application, if the authorization check occurs in middleware. 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. This vulnerability is fixed in 12.3.5, 13.5.9, 14.2.25, and 15.2.3.

A critical vulnerability in Next.js middleware allows attackers to bypass authorization checks by manipulating the x-middleware-subrequest header. This flaw affects Next.js versions prior to 14.2.25 and 15.2.3, potentially granting unauthorized access to sensitive resources.

 id: CVE-2025-29927-HEADLESS

info:
  name: Next.js Middleware Authorization Bypass
  author: ademkin

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