npm · next
Next.js: Server-Side Request Forgery in Server Actions on custom servers
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.
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
Is your project exposed to this? Stateward checks every dependency on every pull request and flags it only if your code actually reaches it.
Check my repoSources: CISA KEV (public domain), OSV.dev & GitHub Advisory Database (CC-BY-4.0), FIRST EPSS, NVD/CWE (public domain). Served live from the Stateward advisory database.