Is there a public exploit for CVE-2026-21884?

No public exploit for CVE-2026-21884 was found in Exploit-DB, Metasploit, Nuclei templates or public proof-of-concept repositories. That is an absence of evidence rather than proof that none exists.

How severe is CVE-2026-21884?

CVE-2026-21884 scores CVSS 8.2 (v3.1), rated high. EPSS puts the chance of exploitation in the next 30 days at 0.53%.

What does CVE-2026-21884 affect?

CVE-2026-21884 affects remix-run react-router, @remix-run/react.

8.2 High

React Router is a router for React.

CVE-2026-21884

A XSS vulnerability exists in in React Router's API in [Framework Mode](https://reactrouter.com/start/modes#framework) 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. [!NOTE] This does not impact applications if developers have [disabled server-side rendering](https://reactrouter.com/how-to/spa) in Framework Mode, or if they are using [Declarative Mode](https://reactrouter.com/start/modes#declarative) ( ) or [Data Mode](https://reactrouter.com/start/modes#data) (createBrowserRouter/ ).

Assessment

CVSS: 8.2 (v3.1)
Severity: High
EPSS: 0.53% chance of exploitation in the next 30 days
Known exploited: Not listed in CISA KEV
Exploit availability: Nothing found in Exploit-DB, Metasploit, Nuclei or public PoC repositories
Published: 8 January 2026
Last updated: 8 September 2026
Affected: remix-run · react-router · react-router · @remix-run/react
Weakness: CWE-79
Assigner: security-advisories@github.com

CVSS vectorCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:H/I:L/A:N

At the source

References

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