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The vulnerability occurs in React Router’s Server-Side Rendering (SSR) when using Framework Mode with the `<BrowserRouter>) and Data Mode (createBrowserRouter or <RouterProvider>) are not affected, nor are applications with SSR disabled. Attackers could exploit this by crafting malicious keys that execute scripts during server rendering, potentially compromising user sessions or stealing data. The issue underscores the importance of validating and sanitizing all inputs used in SSR context, especially in dynamic routing scenarios.
DailyCVE Form:
Platform: React Router
Version: Framework Mode
Vulnerability: SSR XSS
Severity: High
Date: Jan 8, 2026
Prediction: Expected Patch Date: Pending
What Undercode Say:
Analytics:
bash commands and codes related to the blog
Check React Router version in project
npm list react-router-dom
Simulate SSR with vulnerable ScrollRestoration setup
node server.js
Sample code snippet showing vulnerable ScrollRestoration usage
import { ScrollRestoration } from ‘react-router-dom’;
function App() {
return untrustedContent} />;
}
How Exploit:
Attackers inject malicious scripts via untrusted content in getKey/storageKey props during SSR, leading to execution when HTML is served.
Protection from this CVE:
Disable SSR in Framework Mode, avoid untrusted content for keys, use Declarative or Data Mode, sanitize inputs.
Impact:
Arbitrary JavaScript execution, session hijacking, data theft, compromised user trust.
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Sources:
Reported By: github.com
Extra Source Hub:
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