High· 7.5GHSA-fr5h-rqp8-mj6g CVE-2024-34351CWE-918Published May 9, 2024

Next.js Server-Side Request Forgery in Server Actions

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Affected versions

13.4.0 → fixed in 14.1.1

Details

### Impact A Server-Side Request Forgery (SSRF) vulnerability was identified in Next.js Server Actions by security researchers at Assetnote. If the `Host` header is modified, and the below conditions are also met, an attacker may be able to make requests that appear to be originating from the Next.js application server itself. #### Prerequisites * Next.js (`<14.1.1`) is running in a self-hosted* manner. * The Next.js application makes use of Server Actions. * The Server Action performs a redirect to a relative path which starts with a `/`. \* Many hosting providers (including Vercel) route requests based on the Host header, so we do not believe that this vulnerability affects any Next.js applications where routing is done in this manner. ### Patches This vulnerability was patched in [#62561](https://github.com/vercel/next.js/pull/62561) and fixed in Next.js `14.1.1`. ### Workarounds There are no official workarounds for this vulnerability. We recommend upgrading to Next.js `14.1.1`. ### Credit Vercel and the Next.js team thank Assetnote for responsibly disclosing this issue to us, and for working with us to verify the fix. Thanks to: Adam Kues - Assetnote Shubham Shah - Assetnote

The fix

fix redirect

Shu Ding· Feb 26, 2024, 10:06 AM+6−156ba2f4c04

packages/next/src/server/app-render/action-handler.ts+5 −1

@@ -179,9 +179,13 @@ async function createRedirectRenderResult(
     const forwardedHeaders = getForwardedHeaders(req, res)
     forwardedHeaders.set(RSC_HEADER, '1')
  
-    const host = originalHost.value
     const proto =
       staticGenerationStore.incrementalCache?.requestProtocol || 'https'
+ 
+    // For standalone or the serverful mode, use the internal hostname directly
+    // other than the headers from the request.
+    const host = process.env.__NEXT_PRIVATE_HOST || originalHost.value
+ 
     const fetchUrl = new URL(
       `${proto}://${host}${basePath}${parsedRedirectUrl.pathname}`
     )

packages/next/src/server/lib/start-server.ts+1 −0

@@ -246,6 +246,7 @@ export async function startServer(
  
       // expose the main port to render workers
       process.env.PORT = port + ''
+      process.env.__NEXT_PRIVATE_HOST = `${actualHostname}:${port}`
  
       // Only load env and config in dev to for logging purposes
       let envInfo: string[] | undefined

Improve redirection handling (#62561)

Shu Ding· Feb 27, 2024, 05:17 PM+6−18f7a6ca7d2