Information disclosure in Vercel Next.js
CVE-2025-30218
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.
Vulnerability class: Information Disclosure
EPSS: 0.004 (32.5th percentile) — read the EPSS interpretation.
CVSS v3 metric
CVSS v3 base score 5.9 (Medium). Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N.
Affected products
- Vercel Next.js — versions 12.3.5, = 15.2.3, = 14.2.25
Weakness classification (CWE)
References
- security-advisories@github.com (x_refsource_CONFIRM, Vendor Advisory)
- security-advisories@github.com (x_refsource_MISC, Vendor Advisory)
Frequently asked questions
- What is CVE-2025-30218?
- CVE-2025-30218 is a medium-severity vulnerability in Vercel Next.js, classified under Information Disclosure. CVSS score: 5.9/10. Published 2025-04-02.
- How severe is CVE-2025-30218?
- Medium severity. CVSS v3 base score is 5.9 out of 10.