XSS Vulnerability in React Router Affects Remix-Run and React-Router
CVE-2026-21884

8.2HIGH

Key Information:

Vendor

Remix-run

Status
React-router
Vendor
CVE Published:
10 January 2026

What is CVE-2026-21884?

A Cross-Site Scripting (XSS) vulnerability has been identified in React Router's API when used in Framework Mode with the getKey/storageKey props during Server-Side Rendering (SSR). This flaw permits arbitrary JavaScript execution if untrusted content is utilized to create the keys. The issue arises solely when SSR in Framework Mode is enabled, and it does not affect configurations using Declarative Mode or Data Mode. The vulnerability has been addressed in updated versions of the affected packages.

Affected Version(s)

react-router @remix-run/react < 2.17.3 < @remix-run/react 2.17.3

react-router react-router >= 7.0.0, < 7.12.0 < react-router 7.0.0, 7.12.0

References

https://github.com/remix-run/react-router/security/adviso...
x_refsource_CONFIRM

CVSS V3.1

Score:
8.2
Severity:
HIGH
Confidentiality:
High
Integrity:
Low
Availability:
High
Attack Vector:
Network
Attack Complexity:
Low
Privileges Required:
None
User Interaction:
Required
Scope:
Changed

Timeline

  • Vulnerability published

  • Vulnerability Reserved

.