React Router is a router for React. In @remix-run/server-runtime version prior to 2.17.3. and react-router 7.0.0 through 7.11.0, React Router (or Remix v2) is vulnerable to CSRF attacks on document POST requests to UI routes when using server-side route action handlers in Framework Mode, or when using React Server Actions in the new unstable RSC modes. There is no impact if Declarative Mode () or Data Mode (createBrowserRouter/) is being used. This issue has been patched in @remix-run/server-runtime version 2.17.3 and react-router version 7.12.0.
The product does not properly verify that the source of data or communication is valid.