CVE-2026-44581 Next.js: Cross-site scripting in App Router applications using CSP nonces
Attackers can poison cached responses to execute scripts in Next.js App Router applications using CSP nonces, affecting web developers and site visitors.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-44581?
CVE-2026-44581 is a medium-severity cross-site scripting vulnerability in Vercel Next.js, published on 13 May 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
Next.js is a React framework for building full-stack web applications. From 13.4.0 to before 15.5.16 and 16.2.5, App Router applications that rely on CSP nonces can be vulnerable to stored cross-site scripting when deployed behind shared caches. In affected versions, malformed nonce values derived from request headers could be reflected into rendered HTML in an unsafe way, allowing an attacker to poison cached responses and cause script execution for later visitors. This vulnerability is fixed in 15.5.16 and 16.2.5.
Weakness: CWE-79
Which versions are affected by CVE-2026-44581?
4 open source packages ship an affected version, including next. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
next npm | From 13.4.0 | 15.5.16 |
next npm | From 13.4.0 | 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-2026-44581?
Upgrade next to a fixed version for your release line: 15.5.16 or 16.2.5.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-44581 being exploited?
There is no known exploitation of CVE-2026-44581 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-UW85548, CLEANSTART-2026-WK40979, GHSA-ffhc-5mcf-pf4q, MINI-95vg-fhjh-rqfc, MINI-mhwm-g87f-3xj3, MINI-v5fq-qjgx-x55x and 2 more.