What’s Vulnerable › Vulnerabilities

CVE-2026-21884: React Router SSR XSS in ScrollRestoration

• Severity: high (CVSS 8.2 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.5% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-01-10 · updated 2026-07-15
• Weakness: CWE-79

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.

Affected products

• remix-run react-router: from 7.0.0 through 7.11.0
• Shopify Remix-Run/React: before 2.17.3 — fixed in 2.17.3

How to fix

Upgrade to a fixed version: Shopify Remix-Run/React 2.17.3. Check the vendor advisory for mitigations.

References

• https://github.com/remix-run/react-router/security/advisories/GHSA-8v8x-cx79-35w7
• https://access.redhat.com/errata/RHSA-2026:19712
• https://access.redhat.com/errata/RHSA-2026:3782
• https://access.redhat.com/errata/RHSA-2026:3958
• https://access.redhat.com/errata/RHSA-2026:3960
• https://access.redhat.com/security/cve/CVE-2026-21884
• https://bugzilla.redhat.com/show_bug.cgi?id=2428421
• https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-21884.json

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