CVE-2026-21884 React Router SSR XSS in ScrollRestoration
Attackers can execute arbitrary JavaScript during server-side rendering if untrusted content generates ScrollRestoration keys in Framework Mode.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-21884?
CVE-2026-21884 is a high-severity cross-site scripting vulnerability in remix-run react-router, published on 10 Jan 2026. An attacker can exploit it over the internet without logging in, and only if a user opens a file or follows a link.
Official description
React Router is a router for React. In @remix-run/react version prior to 2.17.3. and react-router 7.0.0 through 7.11.0, a XSS vulnerability exists in in React Router's <ScrollRestoration> API in Framework Mode when using the getKey/storageKey props during Server-Side Rendering which could allow arbitrary JavaScript execution during SSR if untrusted content is used to generate the keys. There is no impact if server-side rendering in Framework Mode is disabled, or if Declarative Mode (<BrowserRouter>) or Data Mode (createBrowserRouter/<RouterProvider>) is being used. This issue has been patched in @remix-run/react version 2.17.3 and react-router version 7.12.0.
Weakness: CWE-79
Which versions are affected by CVE-2026-21884?
4 open source packages ship an affected version, including @remix-run/react and react-router. It affects 2 products.
| Package | Affected | Fixed in |
|---|---|---|
@remix-run/react npm | All versions | 2.17.3 |
@remix-run/react npm | All versions | 2.17.3 |
react-router npm | From 7.0.0 | 7.12.0 |
react-router npm | From 7.0.0 | 7.12.0 |
Products include Shopify React-Router, Shopify Remix-Run\/React.
How do I fix CVE-2026-21884?
Upgrade @remix-run/react to 2.17.3 or later.
Escape output for the context it lands in and set a strict Content Security Policy. Upgrading the affected component is the real fix. More about Cross-site scripting.
Is CVE-2026-21884 being exploited?
There is no known exploitation of CVE-2026-21884 in the wild and no public exploit code.
Other vulnerabilities in remix-run react-router
- CVE-2026-55685 React Router: Unauthenticated Denial of Service via Inefficient Route Matching
- CVE-2026-42211 React Router's vendored turbo-stream v2 allows arbitrary constructor invocation via TYPE_ERROR deserialization leading to Unauth RCE
- CVE-2026-33245 React Router vulnerable to XSS in unstable RSC redirect handling via javascript: redirect targets
- CVE-2026-22029 React Router vulnerable to XSS via Open Redirects
- CVE-2025-59057 React Router has XSS Vulnerability
Sources
Also known as GHSA-8v8x-cx79-35w7, ROOT-APP-NPM-CVE-2026-21884.