CVE-2025-30218 Information

Description

Next.js is a React framework for building full-stack web applications. To mitigate CVE-2025-29927 Next.js validated the x-middleware-subrequest-id which persisted across multiple incoming requests. However this subrequest ID is sent to all requests even if the destination is not the same host as the Next.js application. Initiating a fetch request to a third-party within Middleware will send the x-middleware-subrequest-id to that third party. This vulnerability is fixed in 12.3.6 13.5.10 14.2.26 and 15.2.4.

Reference

https://github.com/vercel/next.js/security/advisories/GHSA-223j-4rm8-mrmf https://vercel.com/changelog/cve-2025-30218-5DREmEH765PoeAsrNNQj3O