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

High severity GitHub Reviewed Published Apr 1, 2025 in remix-run/react-router • Updated Apr 1, 2025

Package

npm @react-router/express (npm)

Affected versions

>= 7.0.0, < 7.4.1

Patched versions

7.4.1
npm @remix-run/express (npm)
>= 2.11.1, < 2.16.3
2.16.3

Description

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_)

References

@mjackson mjackson published to remix-run/react-router Apr 1, 2025
Published by the National Vulnerability Database Apr 1, 2025
Published to the GitHub Advisory Database Apr 1, 2025
Reviewed Apr 1, 2025
Last updated Apr 1, 2025

Severity

High

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

EPSS score

Exploit Prediction Scoring System (EPSS)

This score estimates the probability of this vulnerability being exploited within the next 30 days. Data provided by FIRST.
(18th percentile)

Weaknesses

CVE ID

CVE-2025-31137

GHSA ID

GHSA-4q56-crqp-v477

Source code

Credits

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