GHSA-P9FF-H696-F583

Vulnerability from github – Published: 2026-04-06 18:03 – Updated: 2026-04-07 22:16
VLAI?
Summary
Vite Vulnerable to Arbitrary File Read via Vite Dev Server WebSocket
Details

Summary

server.fs check was not enforced to the fetchModule method that is exposed in Vite dev server's WebSocket.

Impact

Only apps that match the following conditions are affected:

  • explicitly exposes the Vite dev server to the network (using --host or server.host config option)
  • WebSocket is not disabled by server.ws: false

Arbitrary files on the server (development machine, CI environment, container, etc.) can be exposed.

Details

If it is possible to connect to the Vite dev server’s WebSocket without an Origin header, an attacker can invoke fetchModule via the custom WebSocket event vite:invoke and combine file://... with ?raw (or ?inline) to retrieve the contents of arbitrary files on the server as a JavaScript string (e.g., export default "...").

The access control enforced in the HTTP request path (such as server.fs.allow) is not applied to this WebSocket-based execution path.

PoC

  1. Start the dev server on the target Example (used during validation with this repository): bash pnpm -C playground/alias exec vite --host 0.0.0.0 --port 5173

  2. Confirm that access is blocked via the HTTP path (example: arbitrary file) bash curl -i 'http://localhost:5173/@fs/etc/passwd?raw' Result: 403 Restricted (outside the allow list) image

  3. Confirm that the same file can be retrieved via the WebSocket path By connecting to the HMR WebSocket without an Origin header and sending a vite:invoke request that calls fetchModule with a file://... URL and ?raw, the file contents are returned as a JavaScript module. image image

Severity ?
8.2 (High)
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N
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{
  "affected": [
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 8.0.4"
      },
      "package": {
        "ecosystem": "npm",
        "name": "vite"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "8.0.0"
            },
            {
              "fixed": "8.0.5"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 7.3.1"
      },
      "package": {
        "ecosystem": "npm",
        "name": "vite"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "7.0.0"
            },
            {
              "fixed": "7.3.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    },
    {
      "database_specific": {
        "last_known_affected_version_range": "\u003c= 6.4.1"
      },
      "package": {
        "ecosystem": "npm",
        "name": "vite"
      },
      "ranges": [
        {
          "events": [
            {
              "introduced": "6.0.0"
            },
            {
              "fixed": "6.4.2"
            }
          ],
          "type": "ECOSYSTEM"
        }
      ]
    }
  ],
  "aliases": [
    "CVE-2026-39363"
  ],
  "database_specific": {
    "cwe_ids": [
      "CWE-200",
      "CWE-306"
    ],
    "github_reviewed": true,
    "github_reviewed_at": "2026-04-06T18:03:24Z",
    "nvd_published_at": "2026-04-07T20:16:30Z",
    "severity": "HIGH"
  },
  "details": "### Summary\n\n[`server.fs`](https://vite.dev/config/server-options#server-fs-strict) check was not enforced to the `fetchModule` method that is exposed in Vite dev server\u0027s WebSocket. \n\n### Impact\n\nOnly apps that match the following conditions are affected:\n\n- explicitly exposes the Vite dev server to the network (using `--host` or [`server.host` config option](https://vitejs.dev/config/server-options.html#server-host))\n- WebSocket is not disabled by `server.ws: false`\n\nArbitrary files on the server (development machine, CI environment, container, etc.) can be exposed.\n\n### Details\n\nIf it is possible to connect to the Vite dev server\u2019s WebSocket **without an `Origin` header**, an attacker can invoke `fetchModule` via the custom WebSocket event `vite:invoke` and combine `file://...` with `?raw` (or `?inline`) to retrieve the contents of arbitrary files on the server as a JavaScript string (e.g., `export default \"...\"`).\n\nThe access control enforced in the HTTP request path (such as `server.fs.allow`) is not applied to this WebSocket-based execution path.\n\n### PoC\n\n1. Start the dev server on the target \n   Example (used during validation with this repository):\n   ```bash\n   pnpm -C playground/alias exec vite --host 0.0.0.0 --port 5173\n   ```\n\n2. Confirm that access is blocked via the HTTP path (example: arbitrary file)\n   ```bash\n   curl -i \u0027http://localhost:5173/@fs/etc/passwd?raw\u0027\n   ```\n   Result: `403 Restricted` (outside the allow list)\n   \u003cimg width=\"3898\" height=\"1014\" alt=\"image\" src=\"https://github.com/user-attachments/assets/f6593377-549c-45d7-b562-5c19833438af\" /\u003e\n\n3. Confirm that the same file can be retrieved via the WebSocket path\n   By connecting to the HMR WebSocket without an `Origin` header and sending a `vite:invoke` request that calls `fetchModule` with a `file://...` URL and `?raw`, the file contents are returned as a JavaScript module.\n  \u003cimg width=\"1049\" height=\"296\" alt=\"image\" src=\"https://github.com/user-attachments/assets/af969f7b-d34e-4af4-8adb-5e2b83b31972\" /\u003e\n  \u003cimg width=\"1382\" height=\"955\" alt=\"image\" src=\"https://github.com/user-attachments/assets/6a230d2e-197a-4c9c-b373-d0129756d5d7\" /\u003e",
  "id": "GHSA-p9ff-h696-f583",
  "modified": "2026-04-07T22:16:11Z",
  "published": "2026-04-06T18:03:24Z",
  "references": [
    {
      "type": "WEB",
      "url": "https://github.com/vitejs/vite/security/advisories/GHSA-p9ff-h696-f583"
    },
    {
      "type": "ADVISORY",
      "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-39363"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vitejs/vite/pull/22159"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vitejs/vite/commit/f02d9fde0b195afe3ea2944414186962fbbe41e0"
    },
    {
      "type": "PACKAGE",
      "url": "https://github.com/vitejs/vite"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vitejs/vite/releases/tag/v6.4.2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vitejs/vite/releases/tag/v7.3.2"
    },
    {
      "type": "WEB",
      "url": "https://github.com/vitejs/vite/releases/tag/v8.0.5"
    }
  ],
  "schema_version": "1.4.0",
  "severity": [
    {
      "score": "CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:N/VA:N/SC:N/SI:N/SA:N",
      "type": "CVSS_V4"
    }
  ],
  "summary": "Vite Vulnerable to Arbitrary File Read via Vite Dev Server WebSocket"
}


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