CVE-2025-31137

Remix and React Router allow URL manipulation via Host / X-Forwarded-Host headers

React Router is a multi-strategy router for React bridging the gap from React 18 to React 19. There is 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. This issue has been patched and released in Remix 2.16.3 and React Router 7.4.1.

Affected

remix-run · react-router

CVSS v3.0 GITHUB

7.5 HIGHCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS

1.17% chance of exploitation in the next 30 days, 67th percentile

Published

2025-04-01

Updated

2025-04-02

Proof-of-concept exploits (1)

• pouriam23/vulnerability-in-Remix-React-Router-CVE-2025-31137-1★ · 2025-04-23

Security advisories

• advisories/GHSA-4q56-crqp-v477

References

• CVE Record
• NVD entry

Related

• CVE-2016-5180
• CVE-2024-12583
• CVE-2025-29927
• CVE-2025-43864