CVE-2026-44574: Vercel Next.js

High severity, CVSS 8.1. EPSS: 0.7% chance of exploitation in the next 30 days.

Next.js is a React framework for building full-stack web applications. From 15.4.0 to before 15.5.16 and 16.2.5, applications that rely on middleware to protect dynamic routes can be vulnerable to authorization bypass. In affected deployments, specially crafted query parameters can alter the dynamic route value seen by the page while leaving the visible path unchanged, which can allow protected content to be rendered without passing the expected middleware check. This vulnerability is fixed in 15.5.16 and 16.2.5.

Affected products

• Vercel Next.js: from 15.4.0, before 15.5.16 (fixed in 15.5.16); from 16.0.0, before 16.2.5 (fixed in 16.2.5)

Published 2026-05-13. Last modified 2026-08-13.