Vite Security

Vite Security Audit

Audit a Vite-based project for security issues specific to Vite's dev server, build pipeline, environment-variable model, and plugin ecosystem. Covers Vite 3 / 4 / 5 / 6.

When this skill applies

• Reviewing vite.config.ts/js/mjs for misconfigurations
• Auditing the env var setup (VITE_ prefix model)
• Checking Vite plugins for known issues
• Reviewing build output for accidentally-shipped secrets or dev-only code
• Auditing Vite dev server exposure (local network, tunnel, demo deployments)
• Confirming production build settings match security expectations

Use other skills for: React/Vue/Svelte component-level issues (react-security, vue-nuxt-security, svelte-sveltekit-security), backend code, deployment platform (vercel-platform-security, cloudflare-workers-security).

Workflow

Follow ../_shared/audit-workflow.md. Vite-specific notes below.

Phase 1: Stack detection

# Detect Vite version
grep -E '"vite":' package.json

# Detect framework template (React/Vue/Svelte/Solid/Qwik)
grep -E '@vitejs/plugin-(react|vue|svelte)|vite-plugin-solid|vite-plugin-qwik' package.json

# Find config
ls vite.config.* vitest.config.* 2>/dev/null

Phase 2: Inventory

# Plugin chain
grep -E 'plugins:|VitePlugin' vite.config.* 

# Env var usage
grep -rn 'import\.meta\.env\.' src/ | head -30

# Define / replace patterns (often used to inject values at build time)
grep -nE 'define:\s*{|process\.env' vite.config.*

# Dev server config (host, port, proxy, allowedHosts)
grep -nE 'server:|preview:' vite.config.*

# Build target & output
grep -nE 'build:|outDir' vite.config.*

Phase 3: Detection — the checks

Environment variables — the VITE_ prefix

Same trap as Next.js's NEXT_PUBLIC_: variables prefixed with VITE_ are exposed to client code at build time. Anything without the prefix is server/build-side only and won't leak.

• VIT-ENV-1 Every VITE_ variable verified as truly public (analytics IDs, public API URLs, feature flags — yes; API keys, secrets, DB URLs — never).
• VIT-ENV-2 No VITE_*_SECRET, VITE_*_KEY, VITE_*_PASSWORD. Audit .env, .env.local, .env.production, and .env.example.
• VIT-ENV-3 Production build inspected for env values:

``bash npm run build grep -rhoE 'VITE_[A-Z_]+|sk_[a-z]+_[A-Za-z0-9]+|AKIA[0-9A-Z]{16}' dist/ | sort -u `` Any values that look secret-shaped in the build are findings.

• VIT-ENV-4 Custom prefix configured via envPrefix — confirm it's the same trap (exposes to bundle). Renaming the prefix doesn't change the security model.
• VIT-ENV-5 define option in vite.config.ts — same risk as VITE_ prefix; the values are inlined into the build. Don't define: { __SECRET__: process.env.SECRET }.

import.meta.env model

// import.meta.env.MODE             — 'development' | 'production' | custom
// import.meta.env.PROD             — true in production
// import.meta.env.DEV              — true in development
// import.meta.env.VITE_FOO         — user-set, ships to bundle
// import.meta.env.SOMETHING        — without VITE_ prefix, undefined in client code

• VIT-ENV-6 Code paths gated only by import.meta.env.DEV ship to production (the check evaluates false, but the surrounding code is still bundled unless dead-code elimination removes it). Sensitive dev-only utilities should be in separate files imported only by dev-time entry points.

Dev server exposure

The Vite dev server is for local development. When it's exposed beyond 127.0.0.1, security issues:

• VIT-DEV-1 server.host: true or server.host: '0.0.0.0' exposes dev server on the LAN. Verify intent (mobile testing? team demo?) and that the network is trusted. Don't expose dev server to public internet via tunnels (ngrok, Cloudflare Tunnel) without understanding the risk.
• VIT-DEV-2 Vite dev server's HMR WebSocket may not have origin validation in older versions — CVE-2023-49293, CVE-2024-23331 (similar class). Update to a current Vite version.
• VIT-DEV-3 server.proxy configs that proxy /api to a backend may expose internal endpoints to anyone reaching the dev server. Don't expose dev servers with proxy enabled.
• VIT-DEV-4 server.fs.allow / server.fs.deny — Vite serves files from disk in dev. The defaults restrict to the project root, but custom configs can broaden the surface. Anything outside the project root → potential file disclosure.

CVE-2025-30208 class: file-read bypass via specific URL patterns. Confirm Vite version is patched.

CVE-2024-31207, CVE-2025-31125, CVE-2025-31486, CVE-2025-32395, CVE-2025-46565, CVE-2025-58751, CVE-2025-58752, CVE-2025-64756 — multiple server.fs and allowedHosts bypasses across 2024–2025. The fix in all cases is updating Vite to a current patch release.

• VIT-DEV-5 server.allowedHosts — used to restrict which Host headers the dev server accepts. Set to specific hostnames; do not use true (allow any) in dev servers reachable beyond localhost.
• VIT-DEV-6 preview server (used for vite preview) is for testing production builds locally. Same exposure considerations as server.

Build configuration

• VIT-BLD-1 build.sourcemap: true in production ships source maps to the CDN. Source maps reveal original code (TypeScript, comments, internal structure). Two acceptable patterns:
• Don't ship source maps to production (set false).
• Ship source maps but upload to a separate location (Sentry) and serve them only to error-tracking, not to public.
• VIT-BLD-2 build.minify: false in production — leaks variable names, comments. Set to 'esbuild' (default) or 'terser'.
• VIT-BLD-3 build.target: 'esnext' may emit code only modern browsers can parse — fine, but verify the deployment surface (older browsers fall off).
• VIT-BLD-4 build.rollupOptions.output.manualChunks configurations — if chunking exposes module names that hint at internal architecture (e.g., admin-internal.js), consider opaque chunk names.

Plugins — supply chain

• VIT-PLG-1 Every plugin in plugins: array is from a known publisher. Vite plugin ecosystem has been targeted by typosquatting and malicious publishes.
• VIT-PLG-2 Plugins pinned to specific versions in package.json with a lockfile.
• VIT-PLG-3 Plugins with broad permissions (file write, network access at build time) reviewed individually. Build-time plugins run with the same privileges as the build user — they can exfiltrate env vars during the build.
• VIT-PLG-4 No plugins from main/master/git URLs (use published npm versions for auditability).

Common plugins worth knowing:

• vite-plugin-pwa — service worker generation; if misconfigured, can cache too aggressively or fail to invalidate.
• vite-plugin-mock — adds API mocking; ensure not enabled in production.
• unplugin-icons — pulls icon packs; verify the icons are from expected sources.
• vite-plugin-checker — type-check during build; dev-only.

Production deployment

• VIT-DEP-1 Built static assets served with appropriate cache headers; immutable file hashes in filenames enable long-term caching.
• VIT-DEP-2 Production build excludes development dependencies (vite, @vitejs/*, test runners) — verify by inspecting node_modules size or package.json for misplaced runtime deps.
• VIT-DEP-3 SPA fallback configured at the host so deep links work; but the fallback doesn't expose vite.config.* or .env* files (always confirm .env* is in .gitignore).
• VIT-DEP-4 Production hosting (Cloudflare Pages, Vercel, Netlify, S3+CloudFront) configured with appropriate security headers — Vite doesn't apply headers; the host does. See saas-security-pack/saas-frontend-hardening.

Mock plugins / dev tooling shipped

• VIT-DEV-7 No vite-plugin-mock, msw setup, or in-app debug routes shipped to production build. Audit dist/ for occurrences:

``bash grep -rE 'mock|msw|__DEBUG__' dist/ ``

Testing — Vitest

• VIT-TST-1 vitest.config.ts doesn't accidentally expose globals that production code consumes (e.g., globals.crypto mocks shouldn't bleed into prod code).
• VIT-TST-2 Test files in node_modules exclusions; test-only fixtures aren't in the source bundle.

Phase 4: Triage

Critical class examples:

• VITE_*_SECRET confirmed in production bundle
• Dev server exposed to public internet
• Vite version with known file-read CVE in use
• Source maps with embedded secrets shipped to CDN
• Build-time plugin exfiltrating env to remote endpoint

Phase 5: Report

Use ../_shared/findings-schema.md. Prefix IDs with VIT-.

References

• references/env-vite-config.md — Detailed env var model, define vs envPrefix, audit techniques

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: hlsitechio
• Source: hlsitechio/claude-skills-security
• License: MIT

Install and usage instructions live in the source repository linked above.