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HIGH severity

GHSA-rxv8-25v2-qmq8 — react-router

HIGHFix: remix-run/react-router@5981192

GHSA-rxv8-25v2-qmq8 is a high-severity (CVSS 7.5) CWE-770 vulnerability in react-router. A fix is available for react-router — see the affected versions and patch details below.

React Router vulnerable to Denial of Service via reflected user input in single-fetch

Also known asCVE-2026-34077
Published
Jun 4, 2026
Updated
Jun 4, 2026
Affected
2 pkgs
Patched
2 / 2
Exploits
None indexed
Exploitation data as of Sep 26, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for GHSA-rxv8-25v2-qmq8.

EPSS Exploitation Probability

via FIRST.org ↗
0.5%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs37th percentile — riskier than 37% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

GHSA-rxv8-25v2-qmq8 by exploitation likelihood (EPSS) against impact (CVSS). Outside the shaded patch-first corner.

Where this sits among everything scored

Of 380,066 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Counts from FIRST.org, log-scaled.

Real-World Exposure

2 pkgs affected

How broadly this vulnerability is actually deployed: weekly install volume shows current usage, and reverse-dependency count shows how many other packages break if it stays unpatched.

9Kother npm packages depend on this — each one inherits the vulnerability until it's patched upstream
react-routernpm
63.5Mdownloads / week
turbo-streamnpm
2.9Mdownloads / week

Description

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>).

Affected Packages

2 total 2 fixed
EcosystemPackageVulnerable rangeFix
📦npmreact-router≥ 7.0.0&&< 7.14.07.14.0npm install react-router@7.14.0
📦npmturbo-streamall versions3.0.0npm install turbo-stream@3.0.0

Affected Products

2 products · 2 configurations
Application
react-routershopify
≥ 7.0.0 && < 7.14.0
range
Application
turbo streamturbo-stream
< 3.0.0
range

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for react-router, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update react-router to 7.14.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-rxv8-25v2-qmq8 is resolved across your whole dependency graph.

  3. Workarounds

    Cap what an attacker can consume: apply request size, rate and timeout limits in front of the affected component, and run it with memory and CPU limits so exhaustion degrades one worker rather than the whole service.

Fixing This On Your OS

If you run this on a Linux distribution, patch through your package manager against the distro's own security advisory below — it tracks the exact backported fix for your release, which can ship on a different timeline (and sometimes a different severity) than the upstream project.

Red HatModerate

React Router is vulnerable to client-side XSS in unstable RSC redirect handling when redirects come from untrusted sources. A remote unauthenticated attacker who can cause a victim to follow a crafted redirect (user interaction required) may execute script in the browser context, leading to denial of service. Only…

ProductFixed inAdvisory
Red Hat Data Grid 8.6.2react-routerRHSA-2026:41951

Frequently Asked Questions

A DoS vulnerability exists in the React Router v7 [Framework Mode](https://reactrouter.com/start/modes#framework), as well as Remix v2.9.0+ with [Single Fetch](https://v2.remix.run/docs/guides/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](https://reactrouter.com/start/modes#declarative) (`<BrowserRouter>`) or [Data Mode](https://r
O3 Security · Impact-Aware SCA

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GHSA-rxv8-25v2-qmq8: react-router (High 7.5) | O3 Security