GHSA-49RJ-9FVP-4H2H

Vulnerability from github – Published: 2026-06-03 21:03 – Updated: 2026-06-03 21:03
VLAI
Summary
React Router's vendored turbo-stream v2 allows arbitrary constructor invocation via TYPE_ERROR deserialization leading to Unauth RCE
Details

When using React Router v7 in Framework Mode, there exists a combination of steps that could potentially allow unauthorized RCE through external requests. This first requires the application code to have an existing prototype pollution vulnerability. This can be leveraged into a 2-step attack in which the second step can trigger unauthorized RCE on the remote server.

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

Severity
8.1 (High)
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 7.14.1"
      },
      "package": {
        "ecosystem": "npm",
        "name": "react-router"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "7.0.0"
            },
            {
              "fixed": "7.14.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-42211"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-502"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-06-03T21:03:32Z",
    "nvd_published_at": "2026-06-02T20:16:36Z",
    "severity": "HIGH"
  },
  "details": "When using React Router v7 in [Framework Mode](https://reactrouter.com/start/modes#framework), there exists a combination of steps that could potentially allow unauthorized RCE through external requests.  This first requires the application code to have an existing prototype pollution vulnerability.  This can be leveraged into a 2-step attack in which the second step can trigger unauthorized RCE on the remote server.\n\n\u003e [!NOTE]\n\u003e This does not impact your React Router application if you are using [Declarative Mode](https://reactrouter.com/start/modes#declarative) (`\u003cBrowserRouter\u003e`) or [Data Mode](https://reactrouter.com/start/modes#data) (`createBrowserRouter`/`\u003cRouterProvider\u003e`).",
  "id": "GHSA-49rj-9fvp-4h2h",
  "modified": "2026-06-03T21:03:32Z",
  "published": "2026-06-03T21:03:32Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/remix-run/react-router/security/advisories/GHSA-49rj-9fvp-4h2h"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-42211"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/remix-run/react-router"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H",
      "type": "CVSS_V3"
    }
  ],
  "summary": "React Router\u0027s vendored turbo-stream v2 allows arbitrary constructor invocation via TYPE_ERROR deserialization leading to Unauth RCE"
}


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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

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  • Confirmed: The vulnerability has been validated from an analyst's perspective.
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