CVE-2026-64649

Next.js: Server-Side Request Forgery in Server Actions on custom servers

Workarounds

If you cannot upgrade, ensure clients do not control the host header your application receives. Pin or validate Host and X-Forwarded-Host at your edge or proxy. On version 14.2.0 and later, you can additionally set the __NEXT_PRIVATE_ORIGIN environment variable to your deployment's real origin:

__NEXT_PRIVATE_ORIGIN=https://www.example.com node server.js

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.

Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside. Typical impact: access to internal metadata services, internal APIs, or cloud credentials.

Kodem intelligence

Already deployed Kodem?

1. What is CVE-2026-64649? CVE-2026-64649 is a high-severity server-side request forgery (SSRF) vulnerability in next (npm), affecting versions >= 14.1.1, < 15.5.21. It is fixed in 15.5.21, 16.2.11. Untrusted input controls the target URL of a server-initiated request, which may reach internal services not otherwise accessible from outside.
2. Which versions of next are affected by CVE-2026-64649? next (npm) versions >= 14.1.1, < 15.5.21 is affected.
3. Is there a fix for CVE-2026-64649? Yes. CVE-2026-64649 is fixed in 15.5.21, 16.2.11. Upgrade to this version or later.
4. Is CVE-2026-64649 exploitable, and should I be worried? Whether CVE-2026-64649 is exploitable in your environment depends on whether the vulnerable code is present and reachable. A CVSS score is a worst-case rating; it does not account for your specific deployment, configuration, or usage patterns. Kodem, an Intelligent Application Security platform, uses runtime intelligence to show which vulnerabilities actually execute in production, so you can focus on the ones that represent real risk. Get a demo
5. What actually determines whether CVE-2026-64649 is exploitable, and how bad it is? Exploitability and impact are not fixed properties of a CVE. They depend on runtime truth: whether the vulnerable code is present, reachable, and actually executes in your application. A high CVSS score on a dependency that never runs is not the same as real risk. Kodem, an Intelligent Application Security platform, uses runtime intelligence to reveal which vulnerabilities actually execute in production, so teams prioritize the ones that genuinely matter.
6. How do I fix CVE-2026-64649?
   • Upgrade next to 15.5.21 or later
   • Upgrade next to 16.2.11 or later

Other vulnerabilities in next