CVE-2025-30218 — MEDIUM (5.9)

Vulnerability 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.

CVSS Score

5.9

MEDIUM

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

Attack Vector

NETWORK

Attack Complexity

HIGH

Privileges Required

NONE

User Interaction

NONE

Scope

UNCHANGED

Confidentiality

HIGH

Integrity

NONE

Availability

NONE

Affected Products

Vendor	Product	Versions
Vercel	Next.Js	12.3.5

Related Weaknesses (CWE)

CWE-200

References

https://github.com/vercel/next.js/security/advisories/GHSA-223j-4rm8-mrmfVendor Advisory
https://vercel.com/changelog/cve-2025-30218-5DREmEH765PoeAsrNNQj3OVendor Advisory

FAQ

What is CVE-2025-30218?

CVE-2025-30218 is a vulnerability with a CVSS score of 5.9 (MEDIUM). 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. H...

How severe is CVE-2025-30218?

CVE-2025-30218 has been rated MEDIUM with a CVSS base score of 5.9/10. Review the CVSS metrics above for detailed severity breakdown.

Is there a patch for CVE-2025-30218?

Check the references section above for vendor advisories and patch information. Affected products include: Vercel Next.Js.