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

Next.js is a React framework for building full-stack web applications. Prior to 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 14.2.25 and 15.2.3.