Skip to content

React Router: RSCErrorHandler Missing Protocol Validation (XSS)

Moderate severity GitHub Reviewed Published Jul 22, 2026 in remix-run/react-router • Updated Jul 23, 2026

Package

npm react-router (npm)

Affected versions

>= 7.11.0, < 7.18.0

Patched versions

7.18.0

Description

This is a follow up to GHSA-8646-j5j9-6r62. React Router was alerted of a code path in the (unstable) RSC error handling path in which redirects from untrusted sources could still result in an XSS vector via attacker-supplied redirect targets

Note

This only affects your application if you are using the unstable RSC APIs

References

@brophdawg11 brophdawg11 published to remix-run/react-router Jul 22, 2026
Published to the GitHub Advisory Database Jul 23, 2026
Reviewed Jul 23, 2026
Last updated Jul 23, 2026

Severity

Moderate

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
High
Privileges required
None
User interaction
Required
Scope
Changed
Confidentiality
High
Integrity
Low
Availability
None

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:3.1/AV:N/AC:H/PR:N/UI:R/S:C/C:H/I:L/A:N

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.
(28th percentile)

Weaknesses

Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. Learn more on MITRE.

CVE ID

CVE-2026-53667

GHSA ID

GHSA-h8fp-f39c-q6mh

Source code

Credits

Loading Checking history
See something to contribute? Suggest improvements for this vulnerability.