# December 3, 2025

## Security update: React Server Components vulnerability patched

We've updated our platform to address a critical security vulnerability (CVE-2025-66478) in React Server Components. This vulnerability, rated CVSS 10.0, could allow remote code execution when processing attacker-controlled requests in unpatched environments.

The vulnerability originates in the upstream React implementation (CVE-2025-55182) and affects Next.js applications using the App Router with React Server Components.

### What we did

We upgraded our platform dependencies to the patched versions:

* **Next.js**: Updated from 15.5.4 to 15.5.7
* **React**: Updated from 19.0.0 to 19.0.1
* **React-DOM**: Updated from 19.0.0 to 19.0.1

These versions include the hardened React Server Components implementation that resolves the vulnerability.

### Impact on Fern users

No action is required from Fern Docs users. The security patch has been applied to all Fern-hosted documentation sites automatically.

For self-hosted deployments, we recommend updating to the latest Fern platform version to ensure you have the security fix.

### References

* [Next.js Security Advisory: CVE-2025-66478](https://nextjs.org/blog/CVE-2025-66478)
* [Next.js 15.5.7 Release](https://github.com/vercel/next.js/releases/tag/v15.5.7)
* [React 19.0.1 Release](https://github.com/facebook/react/releases/tag/v19.0.1)