CVE-2025-29927: Vercel Next.js

Critical severity, CVSS 9.1. EPSS: 99.2% chance of exploitation in the next 30 days.

Next.js is a React framework for building full-stack web applications. Starting in version 1.11.4 and prior to versions 12.3.5, 13.5.9, 14.2.25, and 15.2.3, it is possible to bypass authorization checks within a Next.js application, if the authorization check occurs in middleware. If patching to a safe version is infeasible, it is recommend that you prevent external user requests which contain the x-middleware-subrequest header from reaching your Next.js application. This vulnerability is fixed in 12.3.5, 13.5.9, 14.2.25, and 15.2.3.

Affected products

• Vercel Next.js: from 11.1.4, before 12.3.5 (fixed in 12.3.5); from 13.0.0, before 13.5.9 (fixed in 13.5.9); from 14.0.0, before 14.2.25 (fixed in 14.2.25); from 15.0.0, before 15.2.3 (fixed in 15.2.3)

Published 2025-03-21. Last modified 2026-06-17.