CVE-2026-33244: React router Cross-Site Scripting Vulnerability

MODERATE
Advisory Identifier: GHSA-f22v-gfqf-p8f3
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CVSS 5.4
CWE-79
Published
Advisory Summary

CVE-2026-33244 is a MODERATE (CVSS 5.4) cross-site scripting vulnerability (CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')) affecting React router libraries in the npm ecosystem. The issue involves react router has stored xss via unescaped location header in prerendered redirect html. Remediation is available by upgrading affected packages to version 7.13.2.

CVE-2026-33244 at a Glance

CVE Identifier CVE-2026-33244
GHSA Identifier GHSA-f22v-gfqf-p8f3
Severity MODERATE
CVSS v3.1 Base Score 5.4
CWE Classification CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Affected Product React router
Package Ecosystem npm
Published Date
Last Updated

Security Impact

CVSS: 5.4

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

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

How to Fix CVE-2026-33244

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: 7.13.2 
npm install react-router@7.13.2
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-2026-33244, 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 7.13.2), 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-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting'), where the product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users. 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

When using React Router v7 [Framework Mode](https://reactrouter.com/start/modes#framework) with [Pre-rendering](https://reactrouter.com/how-to/pre-rendering) enabled, an improper neutralization of the HTTP `Location` header value can permit Cross-Site Scripting (XSS) in statically generated HTML files if the redirect location comes from an untrusted source. > [!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-2026-33244 Affected React router Versions

1 component(s)
Fixed Versions:
7.13.2
Product / Package Ecosystem Affected Versions Fixed Version
react-router
npm/react-router
npm
≥ 7.5.1
< 7.13.2
7.13.2

References

GitHub Advisory / Wiki ADVISORY
https://github.com/remix-run/react-router/security/advisories/GHSA-f22v-gfqf-p8f3
NVD — CVE-2026-33244 NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-33244
React router Source Repository REPOSITORY
https://github.com/remix-run/react-router/pull/14880
Security Fix Commit FIX COMMIT
https://github.com/remix-run/react-router/commit/ea28e66926460656815cee9b7f2dfaa872513a8c
React router Source Repository REPOSITORY
https://github.com/remix-run/react-router
React router Source Repository REPOSITORY
https://github.com/remix-run/react-router/blob/react-router%407.13.2/CHANGELOG.md#v7132

Frequently Asked Questions

What is CVE-2026-33244?
CVE-2026-33244 is a security vulnerability in React router involving React Router has stored XSS via unescaped Location header in prerendered redirect HTML under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting').
Which React router versions are affected?
Affected versions include releases prior to 7.13.2 across affected packages: react-router.
What version fixes CVE-2026-33244?
Upgrading to 7.13.2 (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 7.13.2. Upgrade your dependency to 7.13.2 or later.
What is the CVSS score of CVE-2026-33244?
CVE-2026-33244 has a CVSS v3.1 base score of 5.4 (MODERATE) with vector string CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:C/C:L/I:L/A:N.
What CWE is associated with CVE-2026-33244?
CVE-2026-33244 is classified under CWE-79: Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') (The product does not neutralize or incorrectly neutralizes user-controllable input before it is placed in output that is used as a web page that is served to other users.).
How can I check npm dependencies for CVE-2026-33244?
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-f22v-gfqf-p8f3",
  "modified" : "2026-09-08T16:28:02Z",
  "published" : "2026-06-03T20:33:01Z",
  "aliases" : [ "CVE-2026-33244" ],
  "summary" : "React Router has stored XSS via unescaped Location header in prerendered redirect HTML",
  "details" : "When using React Router v7 [Framework Mode](https://reactrouter.com/start/modes#framework) with [Pre-rendering](https://reactrouter.com/how-to/pre-rendering) enabled, an improper neutralization of the HTTP `Location` header value can permit Cross-Site Scripting (XSS) in statically generated HTML files if the redirect location comes from an untrusted source.\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:L/UI:R/S:C/C:L/I:L/A:N"
  } ],
  "affected" : [ {
    "package" : {
      "ecosystem" : "npm",
      "name" : "react-router"
    },
    "ranges" : [ {
      "type" : "ECOSYSTEM",
      "events" : [ {
        "introduced" : "7.5.1"
      }, {
        "fixed" : "7.13.2"
      } ]
    } ]
  } ],
  "references" : [ {
    "type" : "WEB",
    "url" : "https://github.com/remix-run/react-router/security/advisories/GHSA-f22v-gfqf-p8f3"
  }, {
    "type" : "ADVISORY",
    "url" : "https://nvd.nist.gov/vuln/detail/CVE-2026-33244"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/remix-run/react-router/pull/14880"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/remix-run/react-router/commit/ea28e66926460656815cee9b7f2dfaa872513a8c"
  }, {
    "type" : "PACKAGE",
    "url" : "https://github.com/remix-run/react-router"
  }, {
    "type" : "WEB",
    "url" : "https://github.com/remix-run/react-router/blob/react-router%407.13.2/CHANGELOG.md#v7132"
  } ],
  "database_specific" : {
    "cwe_ids" : [ "CWE-79" ],
    "severity" : "MODERATE",
    "github_reviewed" : true,
    "github_reviewed_at" : "2026-06-03T20:33:01Z",
    "nvd_published_at" : "2026-06-02T17:16:28Z"
  }
}