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CVE-2026-21884

8.2 · HIGH

React Router is a router for React.

Published Jan 10, 2026CWE-79EPSS 0.53%

Overview

CVE-2026-21884 is a high-severity vulnerability. It was published on January 10, 2026 and has a CVSS 3.1 base score of 8.2 (HIGH).

This vulnerability has a CVSS 3.1 base score of 8.2, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

Technical description

React Router is a router for React. In @remix-run/react version prior to 2.17.3. and react-router 7.0.0 through 7.11.0, a XSS vulnerability exists in in React Router's <ScrollRestoration> API in Framework Mode when using the getKey/storageKey props during Server-Side Rendering which could allow arbitrary JavaScript execution during SSR if untrusted content is used to generate the keys. There is no impact if server-side rendering in Framework Mode is disabled, or if Declarative Mode (<BrowserRouter>) or Data Mode (createBrowserRouter/<RouterProvider>) is being used. This issue has been patched in @remix-run/react version 2.17.3 and react-router version 7.12.0.

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References

GitHubgithub.com/remix-run/react-router/security/advisories/GHSA-8v8x-cx79-35w7Refaccess.redhat.com/errata/RHSA-2026:19712Refaccess.redhat.com/errata/RHSA-2026:3782Refaccess.redhat.com/errata/RHSA-2026:3958Refaccess.redhat.com/errata/RHSA-2026:3960Refaccess.redhat.com/security/cve/CVE-2026-21884Refbugzilla.redhat.com/show_bug.cgi?id=2428421Refsecurity.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-21884.json

How CyberStrike helps

Frequently asked questions

What is CVE-2026-21884?

CVE-2026-21884 is a high-severity vulnerability. It was published on January 10, 2026 and has a CVSS 3.1 base score of 8.2 (HIGH).

How severe is CVE-2026-21884?

This vulnerability has a CVSS 3.1 base score of 8.2, rated HIGH. It can be exploited remotely over the network. No authentication or special privileges are required for exploitation.

How do I fix or remediate CVE-2026-21884?

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

How can CyberStrike help with CVE-2026-21884?

CyberStrike is an open-source, AI-augmented pentesting engine. Rather than flag a version number, it tests whether an issue like CVE-2026-21884 is actually reachable in your own applications and APIs, then verifies each finding before reporting it. That tells you if the weakness is a real, exploitable risk in your environment or a false positive you can safely deprioritize.

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