CVE-2026-34077 React Router vulnerable to Denial of Service via reflected user input in single-fetch
Attackers can execute arbitrary scripts in user browsers via reflected XSS in React Router's unstable RSC redirect handling.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Over the internet
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-34077?
CVE-2026-34077 is a high-severity cross-site scripting vulnerability in remix-run react-router, published on 2 Jun 2026. An attacker can exploit it over the internet without logging in, with no action from the victim.
Official description
React Router is a router for React. In versions 7.7.0 through 7.13.1, when using React Router's unstable React Server Components (RSC) APIs, there is a potential client-side Cross-Site Scripting (XSS) vulnerability in the RSC redirect handling if redirects come from untrusted sources. This does not impact applications that are not using the unstable RSC APIs in React Router. This is patched in version 7.13.2.
Weakness: CWE-770
Which versions are affected by CVE-2026-34077?
4 open source packages ship an affected version, including react-router and turbo-stream. It affects 2 products.
| Package | Affected | Fixed in |
|---|---|---|
react-router npm | From 7.0.0 | 7.14.0 |
react-router npm | From 7.0.0 | 7.14.0 |
turbo-stream npm | All versions | 3.0.0 |
turbo-stream npm | All versions | 3.0.0 |
Linux distribution packages (1)
agama-web-ui openSUSE:Tumbleweed | All versions | 22+143.ee15dea20-46.1 |
Products include Shopify React-Router, Turbo-Stream Turbo Stream.
How do I fix CVE-2026-34077?
Upgrade react-router to 7.14.0 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-2026-34077 being exploited?
There is no known exploitation of CVE-2026-34077 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-rxv8-25v2-qmq8, MINI-p58x-2x3w-m3gp, ROOT-APP-NPM-CVE-2026-34077, openSUSE-SU-2026:11128-1.