CVE-2026-22030 is a vulnerability classified under CWE-346 (Origin Validation Error) and CWE-352 (Cross-Site Request Forgery) affecting the React Router library and the @remix-run/server-runtime package. React Router is a widely used routing library for React applications, facilitating navigation and UI state management. The vulnerability arises from improper origin validation on document POST requests to UI routes when server-side route action handlers are used in Framework Mode or when React Server Actions are employed in the new unstable React Server Components (RSC) modes. This flaw allows an attacker to craft malicious web pages that can trick authenticated users into submitting forged POST requests to the vulnerable application, potentially causing unauthorized state changes or actions without the user's consent. Importantly, the vulnerability does not impact applications using Declarative Mode (<BrowserRouter>) or Data Mode (createBrowserRouter/<RouterProvider>), which perform proper origin validation. The vulnerability is exploitable remotely without requiring authentication but does require user interaction (e.g., visiting a malicious site). The CVSS v3.1 base score is 6.5, reflecting medium severity due to the lack of confidentiality impact but high integrity impact. The issue was patched in react-router version 7.12.0 and @remix-run/server-runtime 2.17.3. No known exploits have been reported in the wild, but the widespread use of React Router in modern web applications makes this a significant concern for developers and organizations relying on these libraries for routing and server-side actions.

For European organizations, the impact of CVE-2026-22030 can be significant, especially for those developing or deploying React-based web applications using vulnerable versions of react-router or @remix-run/server-runtime in Framework Mode or unstable RSC modes. Successful exploitation could lead to unauthorized state changes, such as modifying user data, performing unintended transactions, or altering application behavior without user consent. This undermines data integrity and could result in reputational damage, regulatory non-compliance (e.g., GDPR violations if personal data is affected), and potential financial losses. Since the vulnerability requires user interaction, phishing or social engineering campaigns could be used to lure users into triggering the CSRF attack. The lack of confidentiality impact reduces the risk of data leakage, but the integrity compromise remains critical for applications handling sensitive operations. European organizations with customer-facing web portals, e-commerce platforms, or internal tools using these libraries are at risk. The absence of known exploits provides a window for proactive patching and mitigation before widespread attacks occur.

1. Immediate upgrade to react-router version 7.12.0 or later and @remix-run/server-runtime version 2.17.3 or later to apply the official patches addressing the origin validation issue. 2. Review application routing configurations to avoid using Framework Mode or unstable React Server Components modes if possible, or ensure that origin validation is properly enforced. 3. Implement additional CSRF protections at the application level, such as anti-CSRF tokens, SameSite cookies, and strict CORS policies to reduce attack surface. 4. Educate developers on secure usage patterns of React Router and Remix frameworks, emphasizing the security implications of different routing modes. 5. Conduct thorough security testing, including penetration testing and code reviews focused on CSRF and origin validation mechanisms. 6. Monitor user activity and logs for unusual POST requests or patterns indicative of CSRF attempts. 7. For organizations unable to immediately patch, consider deploying Web Application Firewalls (WAFs) with custom rules to detect and block suspicious POST requests targeting UI routes. 8. Maintain awareness of updates from the remix-run project and community advisories for any further developments or exploit reports.