CVE-2026-33244 React Router has stored XSS via unescaped Location header in prerendered redirect HTML
Attackers can inject scripts into pre-rendered HTML via unescaped Location headers in React Router Framework Mode, requiring an upgrade to fix.
- Exploited in the wild
- Not known
- Login needed
- Any signed-in user
- Attackable
- Over the internet
- Victim action needed
- A user has to click or open something
- Fix
- Available
What is CVE-2026-33244?
CVE-2026-33244 is a medium-severity cross-site scripting vulnerability in remix-run react-router, published on 2 Jun 2026. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Official description
React Router is a router for React. In versions 7.5.1 through 7.13.1, when using Framework Mode with pre-rendering enabled, improper neutralization of the HTTP `Location` header value can permit Cross-Site Scripting (XSS) in the statically generated HTML files if the redirect location comes from an untrusted source. This does not impact applications using Declarative Mode (`<BrowserRouter>`) or Data Mode (`createBrowserRouter/<RouterProvider>`). This is patched in version 7.13.2.
Weakness: CWE-79
Which versions are affected by CVE-2026-33244?
2 open source packages ship an affected version, including react-router. It affects 1 product.
| Package | Affected | Fixed in |
|---|---|---|
react-router npm | From 7.5.1 | 7.13.2 |
react-router npm | From 7.5.1 | 7.13.2 |
Products include Shopify React-Router.
How do I fix CVE-2026-33244?
Upgrade react-router to 7.13.2 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-2026-33244 being exploited?
There is no known exploitation of CVE-2026-33244 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-2026-21884 React Router SSR XSS in ScrollRestoration
- 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
Sources
Also known as GHSA-f22v-gfqf-p8f3.