Next.js is a React framework for building full-stack web applications. Prior to versions 14.2.32 and 15.4.7, when next() was used without explicitly passing the request object, it could lead to SSRF in self-hosted applications that incorrectly forwarded user-supplied headers. This vulnerability has been fixed in Next.js versions 14.2.32 and 15.4.7. All users implementing custom middleware logic in self-hosted environments are strongly encouraged to upgrade and verify correct usage of the next() function.
https://vercel.com/changelog/cve-2025-57822
https://github.com/vercel/next.js/security/advisories/GHSA-4342-x723-ch2f
https://github.com/vercel/next.js/commit/9c9aaed5bb9338ef31b0517ccf0ab4414f2093d8