Impact

We received a report about a vulnerability in Remix/React Router that affects all Remix 2 and React Router 7 consumers using the Express adapter. Basically, this vulnerability allows anyone to spoof the URL used in an incoming Request by putting a URL pathname in the port section of a URL that is part of a Host or X-Forwarded-Host header sent to a Remix/React Router request handler.

Patches

This issue has been patched and released in Remix 2.16.3 React Router 7.4.1.

Credits

- Rachid Allam (zhero;) - Yasser Allam (inzo)