Vulnerability Details 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.
Exploit prediction scoring system (EPSS) score
EPSS Score 0.0
EPSS Ranking 15.2%
CVSS Severity
CVSS v3 Score 5.9
References
Products affected by CVE-2025-30218
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cpe:2.3:a:vercel:next.js:12.3.5
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cpe:2.3:a:vercel:next.js:13.5.9
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cpe:2.3:a:vercel:next.js:14.2.25
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cpe:2.3:a:vercel:next.js:15.2.3