CVE-2026-42342: React router Denial of Service Vulnerability

HIGH
Advisory Identifier: GHSA-8x6r-g9mw-2r78
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CVSS 7.5
CWE-400
Published
Advisory Summary

CVE-2026-42342 is a HIGH (CVSS 7.5) denial of service vulnerability (CWE-400: Uncontrolled Resource Consumption) affecting React router libraries in the npm ecosystem. The issue involves react router vulnerable to dos via unbounded path expansion in __manifest endpoint. Remediation is available by upgrading affected packages to version 7.15.0, 2.17.5.

CVE-2026-42342 at a Glance

CVE Identifier CVE-2026-42342
GHSA Identifier GHSA-8x6r-g9mw-2r78
Severity HIGH
CVSS v3.1 Base Score 7.5
CWE Classification CWE-400: Uncontrolled Resource Consumption
Affected Product React router
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 7.5

The security impact metrics below are parsed directly from the CVSS v3.1 vector string (CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H).

Attack Vector Network (AV:N)
Attack Complexity Low (AC:L)
Privileges Required None (PR:N)
User Interaction None (UI:N)
Scope Unchanged (S:U)
Confidentiality None (C:N)
Integrity None (I:N)
Availability High (A:H)

How to Fix CVE-2026-42342

To remediate this vulnerability, upgrade all affected React router dependencies to a patched release. Both direct and transitive dependencies should be checked, as frameworks or security libraries may pull in vulnerable versions transitively.

react-router fixed: 7.15.0 
npm install react-router@7.15.0
@remix-run/server-runtime fixed: 2.17.5 
npm install @remix-run/server-runtime@2.17.5
Verify Direct and Transitive Dependencies

Run the following command in your project directory to verify that all resolved dependencies use the patched release: 

npm ls react-router

How to Check if You Are Affected

To determine whether your Node.js application is affected by CVE-2026-42342, inspect your project dependencies using npm:

npm ls react-router

Analyze the terminal output to locate any version of React router in your dependency tree. If any resolved version matches the vulnerable ranges listed in the table below (for example, versions earlier than 7.15.0), your application is affected.

Note: The npm ls react-router command inspects dependencies declared in your package.json and lockfile; it does not perform automated runtime dynamic scanning.

Technical Details

Vulnerability Mechanism & Technical Analysis

This vulnerability is classified under CWE-400: Uncontrolled Resource Consumption, where the product does not properly control the allocation and maintenance of a limited resource. In React router, software state validation or input boundaries are circumvented during processing. Review the official source advisory statement below for specific affected components, classes, and reproduction details.

Source Advisory Statement

There exists a potential DOS attack vector in React Router Framework Mode applications (as well as Remix v2.10.0 - 2.17.4). Certain requests can be crafted to consume disproportionate resources on the server, resulting in response time degredation and/or service unavailability for end users. > [!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://reactrouter.com/start/modes#data) (`createBrowserRouter`/`<RouterProvider>`).

CVE-2026-42342 Affected React router Versions

2 component(s)
Fixed Versions:
7.15.02.17.5
Product / Package Ecosystem Affected Versions Fixed Version
react-router
npm/react-router
npm
≥ 7.0.0
< 7.15.0
7.15.0
@remix-run/server-runtime
npm/@remix-run/server-runtime
npm
≥ 2.10.0
< 2.17.5
2.17.5

References

GitHub Advisory / Wiki ADVISORY
https://github.com/remix-run/react-router/security/advisories/GHSA-8x6r-g9mw-2r78
NVD — CVE-2026-42342 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-42342
React router Source Repository REPOSITORY
https://github.com/remix-run/react-router

Frequently Asked Questions

What is CVE-2026-42342?
CVE-2026-42342 is a security vulnerability in React router involving React Router vulnerable to DoS via unbounded path expansion in __manifest endpoint under CWE-400: Uncontrolled Resource Consumption.
Which React router versions are affected?
Affected versions include releases prior to 7.15.0, 2.17.5 across affected packages: react-router, @remix-run/server-runtime.
What version fixes CVE-2026-42342?
Upgrading to 7.15.0, 2.17.5 (or the latest patched release for your respective branch) resolves the vulnerability.
Is react-router affected?
Yes, react-router is affected in releases prior to 7.15.0. Upgrade your dependency to 7.15.0 or later.
Is @remix-run/server-runtime affected?
Yes, @remix-run/server-runtime is affected in releases prior to 2.17.5. Upgrade your dependency to 2.17.5 or later.
What is the CVSS score of CVE-2026-42342?
CVE-2026-42342 has a CVSS v3.1 base score of 7.5 (HIGH) with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H.
What CWE is associated with CVE-2026-42342?
CVE-2026-42342 is classified under CWE-400: Uncontrolled Resource Consumption (The product does not properly control the allocation and maintenance of a limited resource.).
How can I check npm dependencies for CVE-2026-42342?
Run the dependency tree command: 'npm ls react-router'. This command lists direct and transitive dependencies in your build configuration so you can verify if a vulnerable version is resolved.
Machine-readable OSV JSON OSV v1.5 Schema
Normalized schema output
View Raw JSON 
{
  "schema_version" : "1.4.0",
  "id" : "GHSA-8x6r-g9mw-2r78",
  "modified" : "2026-06-03T21:05:17Z",
  "published" : "2026-06-03T21:05:17Z",
  "aliases" : [ "CVE-2026-42342" ],
  "summary" : "React Router vulnerable to DoS via unbounded path expansion in __manifest endpoint",
  "details" : "There exists a potential DOS attack vector in React Router Framework Mode applications (as well as Remix v2.10.0 - 2.17.4).  Certain requests can be crafted to consume disproportionate resources on the server, resulting in response time degredation and/or service unavailability for end users.\n\n> [!NOTE]\n> 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://reactrouter.com/start/modes#data) (`createBrowserRouter`/`<RouterProvider>`).",
  "severity" : [ {
    "type" : "CVSS_V3",
    "score" : "CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "react-router"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "7.0.0"
      }, {
        "fixed" : "7.15.0"
      } ]
    } ]
  }, {
    "package" : {
      "ecosystem" : "npm",
      "name" : "@remix-run/server-runtime"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "2.10.0"
      }, {
        "fixed" : "2.17.5"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/remix-run/react-router/security/advisories/GHSA-8x6r-g9mw-2r78"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-42342"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/remix-run/react-router"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-400" ],
    "severity" : "HIGH",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-03T21:05:17Z",
    "nvd_published_at" : "2026-06-02T20:16:36Z"
  }
}