React Router vulnerable to Denial of Service via reflected user input in single-fetch
A DoS vulnerability exists in the React Router v7 [Framework Mode](https://reactrouter.com/start/modes#framework), as well as Remix v2.9.0+ with [Single Fetch](https://v2.remix.run/docs/guides/single-fetch) enabled. In some scenarios the underlying serialization algorithm can become a bottleneck when encoding specific types of data into server responses. Please upgrade to React Router v7.14.0 or later. > [!NOTE] > This does not impact your React Router application if you are using [Declarative Mode](https://reactrouter.com/start/modes#declarative) (`<BrowserRouter>`) or [Data Mode](https://reactrouter.com/start/modes#data) (`createBrowserRouter`/`<RouterProvider>`).
describes (1)
Related CVEs.
| ID | severity | exploitable | ||
|---|---|---|---|---|
| CVE-2026-34077US | — | — | ||
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-… | ||||
references
External citations — patches, advisories, analysis.
- https://github.com/jacob-ebey/turbo-stream/blob/v2.4.1/src/flatten.ts#L175-L177WEB
- https://github.com/jacob-ebey/turbo-stream/blob/v2.4.1/src/unflatten.ts#L185-L189WEB
- https://github.com/remix-run/react-routerPACKAGE
- https://github.com/remix-run/react-router/commit/59811921d3c7d599077b8cadccdcd65a233165e0WEB
- https://github.com/remix-run/react-router/security/advisories/GHSA-rxv8-25v2-qmq8WEB
- https://nvd.nist.gov/vuln/detail/CVE-2026-34077ADVISORY
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