CVE-2026-22030: React Router CSRF Vulnerability

CVE-2026-22030 Overview

A Cross-Site Request Forgery (CSRF) vulnerability has been identified in React Router, affecting @remix-run/server-runtime versions prior to 2.17.3 and react-router versions 7.0.0 through 7.11.0. The vulnerability allows attackers to perform CSRF attacks on document POST requests to UI routes when applications use server-side route action handlers in Framework Mode or React Server Actions in unstable RSC modes.

Critical Impact

Attackers can forge requests on behalf of authenticated users to execute unauthorized actions via malicious POST requests to vulnerable React Router applications using Framework Mode or RSC modes.

Affected Products

• @remix-run/server-runtime versions prior to 2.17.3
• react-router versions 7.0.0 through 7.11.0
• Applications using Framework Mode with server-side route action handlers or unstable RSC modes

Discovery Timeline

• 2026-01-10 - CVE CVE-2026-22030 published to NVD
• 2026-01-13 - Last updated in NVD database

Technical Details for CVE-2026-22030

Vulnerability Analysis

This CSRF vulnerability (CWE-346: Origin Validation Error) affects React Router applications that utilize server-side route action handlers. The flaw stems from insufficient origin validation when processing document POST requests to UI routes. Applications running in Framework Mode or using React Server Actions in unstable RSC modes are susceptible to forged cross-origin requests.

Importantly, applications using Declarative Mode (<BrowserRouter>) or Data Mode (createBrowserRouter/<RouterProvider>) are not affected by this vulnerability. The issue specifically targets the server-side request handling mechanisms in Framework Mode configurations.

Root Cause

The vulnerability originates from improper origin validation in the request handling pipeline for server-side route actions. When processing incoming POST requests to UI routes, the affected versions fail to properly verify the request origin, allowing cross-site requests to bypass security controls. This weakness is classified as CWE-346 (Origin Validation Error), indicating that the application does not adequately validate the source of incoming requests before processing them.

Attack Vector

The attack is network-based and requires user interaction. An attacker can craft a malicious webpage containing a form or JavaScript that submits POST requests to a vulnerable React Router application. When an authenticated user visits the attacker's page, the malicious request is sent to the target application with the victim's credentials, potentially triggering unauthorized actions through the server-side route handlers.

The exploitation mechanism involves:

1. Attacker creates a malicious page with a hidden form targeting the victim application's route action endpoint
2. Victim user, authenticated to the target application, visits the attacker's page
3. The malicious form auto-submits a POST request to the vulnerable route
4. The server-side action handler processes the request without proper origin validation
5. Unauthorized actions are executed with the victim's session context

For detailed technical information about the exploitation mechanism, refer to the GitHub Security Advisory.

Detection Methods for CVE-2026-22030

Indicators of Compromise

• Unexpected POST requests to server-side route action endpoints from external referrers
• Unusual form submission patterns from untrusted origins
• Server logs showing POST requests with mismatched or missing origin headers
• Anomalous state changes triggered by route actions without corresponding user activity

Detection Strategies

• Monitor server access logs for POST requests to route action endpoints with external Referer headers
• Implement origin header validation alerts in web application firewalls (WAF)
• Review application audit logs for unexpected state modifications via route actions
• Deploy SentinelOne Singularity to detect and correlate suspicious request patterns across your infrastructure

Monitoring Recommendations

• Enable detailed logging for all server-side route action invocations
• Configure alerting for POST requests with missing or mismatched Origin headers
• Monitor for sudden increases in cross-origin requests to framework-mode routes
• Implement session-based activity correlation to detect unauthorized action execution

How to Mitigate CVE-2026-22030

Immediate Actions Required

• Upgrade @remix-run/server-runtime to version 2.17.3 or later
• Upgrade react-router to version 7.12.0 or later
• Audit applications to identify usage of Framework Mode or RSC modes with server-side route actions
• Review recent route action logs for potential exploitation indicators

Patch Information

The vulnerability has been addressed in the following versions:

For complete patch details and release notes, see the GitHub Security Advisory.

Workarounds

• Migrate to Declarative Mode (<BrowserRouter>) or Data Mode (createBrowserRouter/<RouterProvider>) if upgrading is not immediately possible
• Implement custom CSRF token validation in server-side route action handlers
• Add origin validation middleware to filter requests from untrusted sources
• Configure Content Security Policy headers to restrict form submissions to same-origin

# Update packages to patched versions
npm update @remix-run/server-runtime@2.17.3
npm update react-router@7.12.0

# Or using yarn
yarn upgrade @remix-run/server-runtime@2.17.3
yarn upgrade react-router@7.12.0