CVE-2026-44574 Next.js: Middleware / Proxy bypass through dynamic route parameter injection
Attackers can bypass middleware authorization checks on dynamic routes via crafted query parameters, accessing protected content in Next.js applications.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-44574?
CVE-2026-44574 is a high-severity authentication bypass vulnerability in Vercel Next.js, published on 13 May 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Official description
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.
Which versions are affected by CVE-2026-44574?
4 open source packages ship an affected version, including next. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
next npm | From 15.4.0 | 15.5.16 |
next npm | From 15.4.0 | 15.5.16 |
next npm | From 16.0.0 | 16.2.5 |
next npm | From 16.0.0 | 16.2.5 |
Products include Vercel Next.js.
How do I fix CVE-2026-44574?
Upgrade next to a fixed version for your release line: 15.5.16 or 16.2.5.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-44574 being exploited?
There is no known exploitation of CVE-2026-44574 in the wild and no public exploit code.
Other vulnerabilities in Vercel Next.js
- CVE-2025-29927 Authorization Bypass in Next.js Middleware
- CVE-2026-44578 Next.js: Server-side request forgery in applications using WebSocket upgrades
- CVE-2026-94483 Next.js: Server-Side Request Forgery in Image Optimization
- CVE-2026-64642 Next.js: Middleware / Proxy bypass in App Router applications using Turbopack and single locale
- CVE-2026-64645 Next.js: Server-Side Request Forgery in rewrites via attacker-controlled destination hostname
Sources
Also known as CLEANSTART-2026-NX51589, CLEANSTART-2026-TE19253, GHSA-492v-c6pp-mqqv, MINI-2r99-xxj6-258r, MINI-3cx8-h6xg-2vx9, MINI-h824-8mhf-m29r and 2 more.