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GHSA-49rj-9fvp-4h2h

React Router's vendored turbo-stream v2 allows arbitrary constructor invocation via TYPE_ERROR deserialization leading to Unauth RCE

Source: GitHub Advisory Database (reviewed) High CVE-2026-42211

Packages

EcosystemPackageAffectedFixed in
npm react-router >= 7.0.0, < 7.14.2 7.14.2

Details

As written in the advisory (Markdown source, shown as plain text).

When using React Router v7 in [Framework Mode](https://reactrouter.com/start/modes#framework), there exists a combination of steps that could potentially allow unauthorized RCE through external requests. This first requires the application code to have an existing prototype pollution vulnerability. This can be leveraged into a 2-step attack in which the second step can trigger unauthorized RCE on the remote server. > [!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>`).

References

External links from the advisory. They lead to third-party sites.