CVE-2026-64649 Next.js: Server-Side Request Forgery in Server Actions on Custom Servers
Attackers can force Next.js servers to send requests to malicious hosts via Server Actions, potentially exposing internal data or bypassing authorization.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-64649?
CVE-2026-64649 is a high-severity server-side request forgery vulnerability in Vercel Next.js, published on 27 Jul 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
Next.js is a React framework for building full-stack web applications. In versions 14.1.1 through 15.5.20 and 16.0.0 through 16.2.10, when a Server Action forwards or redirects a request, an attacker can cause the server to send that outbound request to a malicious host (Server-Side Request Forgery). This requires the attacker's request to control Host-associated headers. In some configurations, it's also possible to obtain internal values that weaken middleware/proxy authorization. Applications that use Server Actions are affected when the incoming host header is not fixed to a trusted value. This typically occurs on custom servers, or on deployments not behind a proxy that pins the host. Managed hosting pins the host upstream and is not affected; next start and standalone output do the same from version 14.2 onward. This issue has been fixed in versions 15.5.21 and 16.2.11.
Weakness: CWE-918
Which versions are affected by CVE-2026-64649?
4 open source packages ship an affected version, including next. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
next npm | From 14.1.1 | 15.5.21 |
next npm | From 14.1.1 | 15.5.21 |
next npm | From 16.0.0 | 16.2.11 |
next npm | From 16.0.0 | 16.2.11 |
Products include Vercel Next.js.
How do I fix CVE-2026-64649?
Upgrade next to a fixed version for your release line: 15.5.21 or 16.2.11.
Upgrade, and send outbound requests through an allow-list that blocks internal addresses. More about Server-side request forgery.
Is CVE-2026-64649 being exploited?
There is no known exploitation of CVE-2026-64649 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-KK18205, CLEANSTART-2026-KT00157, ECHO-0663-1480-e28f, GHSA-89xv-2m56-2m9x, MINI-cc4r-gw7f-xjv3, MINI-rfmj-vrxv-65xj and 3 more.