CVE-2026-34077: React Router vulnerable to Denial of Service via reflected user input in single-fetch

Published Jun 2, 2026
·
Updated

A DoS vulnerability exists in the React Router v7 Framework Mode, as well as Remix v2.9.0+ with Single Fetch enabled. In some scenarios the underlying serialization algorithm can become a bottleneck when encoding specific types of data into server responses. Please upgrade to React Router v7.14.0 or later.

> [!NOTE] > This does not impact your React Router application if you are using Declarative Mode (<BrowserRouter>) or Data Mode (createBrowserRouter/<RouterProvider>).

Other sources

React Router is a router for React. In versions 7.7.0 through 7.13.1, when using React Router's unstable React Server Components (RSC) APIs, there is a potential client-side Cross-Site Scripting (XSS) vulnerability in the RSC redirect handling if redirects come from untrusted sources. This does not impact applications that are not using the unstable RSC APIs in React Router. This is patched in version 7.13.2.

— NVD

Affected Software

8 affected componentsFixes available
npm/react-router>=7.7.0<=7.13.1
npm/turbo-stream<3.0.0
3.0.0
npm/react-router>=7.0.0<7.14.0
7.14.0
Shopify React-router Node.js>=7.0.0<7.14.0
Turbo-stream Turbo Stream Node.js<3.0.0
IBM Engineering AI Hub<=1.0.0
IBM Engineering AI Hub<=1.1.0
IBM Engineering AI Hub<=1.2.0

Remediation

Recommended actions to resolve this vulnerability, in priority order.

  1. Upgrade

    Upgrade npm/turbo-stream to a version that resolves this vulnerability.

    Fixed in 3.0.0
  2. Upgrade

    Upgrade npm/react-router to a version that resolves this vulnerability.

    Fixed in 7.14.0
  3. Upgrade

    Upgrade React Router to a version that resolves this vulnerability.

    Fixed in 7.14.0
  4. Upgrade

    Upgrade React Router to a version that resolves this vulnerability.

    Fixed in 7.13.2

Event History

Jun 2, 2026
CVE Published
via MITRE·05:31 PM
Data Sourced
via MITRE·05:31 PM
DescriptionSeverityWeakness
Data Sourced
via Red Hat·08:02 PM
DescriptionSeverityAffected Software
Data Sourced
via NVD·08:16 PM
DescriptionSeverityWeaknessAffected Software
Jun 4, 2026
Advisory Published
via GitHub·03:23 PM
Data Sourced
via GitHub·03:23 PM
DescriptionSeverityWeaknessAffected Software
Jul 14, 2026
Data Sourced
via IBM·12:00 AM
DescriptionAffected Software

Parent advisories

This vulnerability appears in the following advisories.

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Frequently Asked Questions

1

What is the severity of CVE-2026-34077?

The severity of CVE-2026-34077 is classified as high with a score of 7.5.

2

How do I fix CVE-2026-34077?

To fix CVE-2026-34077, upgrade your React Router to version 7.13.2 or later.

3

What types of attacks can CVE-2026-34077 facilitate?

CVE-2026-34077 can facilitate Denial of Service attacks through reflected user input in single-fetch scenarios.

4

Which versions of React Router are affected by CVE-2026-34077?

CVE-2026-34077 affects React Router versions from 7.7.0 to 7.13.1.

5

Is user input from untrusted sources a risk factor for CVE-2026-34077?

Yes, untrusted sources of user input significantly increase the risk associated with CVE-2026-34077.

Company

Resources

Contact

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