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Security Advisories: GSA_kwCzR0hTQS05MnIzLW0ybWctcGo5N84AA3lD

Vite XSS vulnerability in `server.transformIndexHtml` via URL payload

Summary

When Vite's HTML transformation is invoked manually via server.transformIndexHtml, the original request URL is passed in unmodified, and the html being transformed contains inline module scripts (<script type="module">...</script>), it is possible to inject arbitrary HTML into the transformed output by supplying a malicious URL query string to server.transformIndexHtml.

Impact

Only apps using appType: 'custom' and using the default Vite HTML middleware are affected. The HTML entry must also contain an inline script. The attack requires a user to click on a malicious URL while running the dev server. Restricted files aren't exposed to the attacker.

Patches

Fixed in [email protected], [email protected], [email protected]

Details

Suppose index.html contains an inline module script:

<script type="module">
  // Inline script
</script>

This script is transformed into a proxy script like

<script type="module" src="/index.html?html-proxy&index=0.js"></script>

due to Vite's HTML plugin:

https://github.com/vitejs/vite/blob/7fd7c6cebfcad34ae7021ebee28f97b1f28ef3f3/packages/vite/src/node/plugins/html.ts#L429-L465

When appType: 'spa' | 'mpa', Vite serves HTML itself, and htmlFallbackMiddleware rewrites req.url to the canonical path of index.html,

https://github.com/vitejs/vite/blob/73ef074b80fa7252e0c46a37a2c94ba8cba46504/packages/vite/src/node/server/middlewares/htmlFallback.ts#L44-L47

so the url passed to server.transformIndexHtml is /index.html.

However, if appType: 'custom', HTML is served manually, and if server.transformIndexHtml is called with the unmodified request URL (as the SSR docs suggest), then the path of the transformed html-proxy script varies with the request URL. For example, a request with path / produces

<script type="module" src="/@id/__x00__/index.html?html-proxy&index=0.js"></script>

It is possible to abuse this behavior by crafting a request URL to contain a malicious payload like

"></script><script>alert('boom')</script>

so a request to http://localhost:5173/?%22%3E%3C/script%3E%3Cscript%3Ealert(%27boom%27)%3C/script%3E produces HTML output like

<script type="module" src="/@id/__x00__/?"></script><script>alert("boom")</script>?html-proxy&index=0.js"></script>

which demonstrates XSS.

PoC

Example 1. Serving HTML from vite dev middleware with appType: 'custom'
- Go to https://stackblitz.com/edit/vitejs-vite-9xhma4?file=main.js&terminal=dev-html
- "Open in New Tab"
- Edit URL to set query string to ?%22%3E%3C/script%3E%3Cscript%3Ealert(%27boom%27)%3C/script%3E and navigate
- Witness XSS:
Example 2. Serving HTML from SSR-style Express server (Vite dev server runs in middleware mode):
- Go to https://stackblitz.com/edit/vitejs-vite-9xhma4?file=main.js&terminal=server
- (Same steps as above)
Example 3. Plain vite dev (this shows that vanilla vite dev is not vulnerable, provided htmlFallbackMiddleware is used)
- Go to https://stackblitz.com/edit/vitejs-vite-9xhma4?file=main.js&terminal=dev
- (Same steps as above)
- You should not see the alert box in this case

Detailed Impact

This will probably predominantly affect development-mode SSR, where vite.transformHtml is called using the original req.url, per the docs:

https://github.com/vitejs/vite/blob/7fd7c6cebfcad34ae7021ebee28f97b1f28ef3f3/docs/guide/ssr.md?plain=1#L114-L126

However, since this vulnerability affects server.transformIndexHtml, the scope of impact may be higher to also include other ad-hoc calls to server.transformIndexHtml from outside of Vite's own codebase.

My best guess at bisecting which versions are vulnerable involves the following test script

import fs from 'node:fs/promises';
import * as vite from 'vite';

const html = `
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
  </head>
  <body>
    <script type="module">
      // Inline script
    </script>
  </body>
</html>
`;
const server = await vite.createServer({ appType: 'custom' });
const transformed = await server.transformIndexHtml('/?%22%3E%3C/script%3E%3Cscript%3Ealert(%27boom%27)%3C/script%3E', html);
console.log(transformed);
await server.close();

and using it I was able to narrow down to #13581. If this is correct, then vulnerable Vite versions are 4.4.0-beta.2 and higher (which includes 4.4.0).

Permalink: https://github.com/advisories/GHSA-92r3-m2mg-pj97
JSON: https://advisories.ecosyste.ms/api/v1/advisories/GSA_kwCzR0hTQS05MnIzLW0ybWctcGo5N84AA3lD
Source: GitHub Advisory Database
Origin: Unspecified
Severity: Moderate
Classification: General
Published: 5 months ago
Updated: 5 months ago

CVSS Score: 6.1
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N

Identifiers: GHSA-92r3-m2mg-pj97, CVE-2023-49293
References:

Repository: https://github.com/vitejs/vite
Blast Radius: 33.9

Affected Packages

npm:vite

Dependent packages: 31,388
Dependent repositories: 363,358
Downloads: 52,043,674 last month
Affected Version Ranges: >= 5.0.0, < 5.0.5, = 4.5.0, >= 4.4.0, < 4.4.12
Fixed in: 5.0.5, 4.5.1, 4.4.12
All affected versions: 4.4.0, 4.4.1, 4.4.2, 4.4.3, 4.4.4, 4.4.5, 4.4.6, 4.4.7, 4.4.8, 4.4.9, 4.4.10, 4.4.11, 4.5.0, 5.0.0, 5.0.1, 5.0.2, 5.0.3, 5.0.4
All unaffected versions: 0.1.0, 0.1.1, 0.1.2, 0.2.0, 0.3.0, 0.3.1, 0.3.2, 0.4.0, 0.5.0, 0.5.1, 0.5.2, 0.5.3, 0.6.0, 0.6.1, 0.7.0, 0.8.0, 0.8.1, 0.9.0, 0.9.1, 0.10.0, 0.10.1, 0.10.2, 0.10.3, 0.11.0, 0.11.1, 0.11.2, 0.11.3, 0.11.4, 0.11.5, 0.12.0, 0.13.0, 0.13.1, 0.13.2, 0.14.0, 0.14.1, 0.14.2, 0.14.3, 0.14.4, 0.15.0, 0.15.1, 0.15.2, 0.15.3, 0.15.4, 0.15.5, 0.15.6, 0.16.0, 0.16.1, 0.16.2, 0.16.3, 0.16.4, 0.16.5, 0.16.6, 0.16.7, 0.16.8, 0.16.9, 0.16.10, 0.16.11, 0.16.12, 0.17.0, 0.17.1, 0.17.2, 0.18.0, 0.18.1, 0.19.0, 0.19.1, 0.19.2, 0.19.3, 0.20.0, 0.20.1, 0.20.2, 0.20.3, 0.20.4, 0.20.5, 0.20.6, 0.20.7, 0.20.8, 0.20.9, 0.20.10, 2.0.0, 2.0.1, 2.0.2, 2.0.3, 2.0.4, 2.0.5, 2.1.0, 2.1.1, 2.1.2, 2.1.3, 2.1.4, 2.1.5, 2.2.0, 2.2.1, 2.2.2, 2.2.3, 2.2.4, 2.3.0, 2.3.1, 2.3.2, 2.3.3, 2.3.4, 2.3.5, 2.3.6, 2.3.7, 2.3.8, 2.4.0, 2.4.1, 2.4.2, 2.4.3, 2.4.4, 2.5.0, 2.5.1, 2.5.2, 2.5.3, 2.5.4, 2.5.5, 2.5.6, 2.5.7, 2.5.8, 2.5.9, 2.5.10, 2.6.0, 2.6.1, 2.6.2, 2.6.3, 2.6.4, 2.6.5, 2.6.6, 2.6.7, 2.6.8, 2.6.9, 2.6.10, 2.6.11, 2.6.12, 2.6.13, 2.6.14, 2.7.0, 2.7.1, 2.7.2, 2.7.3, 2.7.4, 2.7.5, 2.7.6, 2.7.7, 2.7.8, 2.7.9, 2.7.10, 2.7.11, 2.7.12, 2.7.13, 2.8.0, 2.8.1, 2.8.2, 2.8.3, 2.8.4, 2.8.5, 2.8.6, 2.9.0, 2.9.1, 2.9.2, 2.9.3, 2.9.4, 2.9.5, 2.9.6, 2.9.7, 2.9.8, 2.9.9, 2.9.10, 2.9.11, 2.9.12, 2.9.13, 2.9.14, 2.9.15, 2.9.16, 2.9.17, 2.9.18, 3.0.0, 3.0.1, 3.0.2, 3.0.3, 3.0.4, 3.0.5, 3.0.6, 3.0.7, 3.0.8, 3.0.9, 3.1.0, 3.1.1, 3.1.2, 3.1.3, 3.1.4, 3.1.5, 3.1.6, 3.1.7, 3.1.8, 3.2.0, 3.2.1, 3.2.2, 3.2.3, 3.2.4, 3.2.5, 3.2.6, 3.2.7, 3.2.8, 3.2.10, 4.0.0, 4.0.1, 4.0.2, 4.0.3, 4.0.4, 4.0.5, 4.1.0, 4.1.1, 4.1.2, 4.1.3, 4.1.4, 4.1.5, 4.2.0, 4.2.1, 4.2.2, 4.2.3, 4.3.0, 4.3.1, 4.3.2, 4.3.3, 4.3.4, 4.3.5, 4.3.6, 4.3.7, 4.3.8, 4.3.9, 4.4.12, 4.5.1, 4.5.2, 4.5.3, 5.0.5, 5.0.6, 5.0.7, 5.0.8, 5.0.9, 5.0.10, 5.0.11, 5.0.12, 5.0.13, 5.1.0, 5.1.1, 5.1.2, 5.1.3, 5.1.4, 5.1.5, 5.1.6, 5.1.7, 5.2.0, 5.2.1, 5.2.2, 5.2.3, 5.2.4, 5.2.5, 5.2.6, 5.2.7, 5.2.8, 5.2.9, 5.2.10