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Lovable.dev Data Leak: How to Check if Your App Is Leaking User Data

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OverMCP Team

Is My Lovable.dev App Leaking User Data?

TL;DR: Yes, it's possible. Lovable.dev apps—especially those built quickly with AI prompts—often leak user data via exposed API keys, permissive CORS policies, unprotected admin routes, and verbose error messages. You can check for these leaks in under 10 minutes using browser DevTools and a few manual tests.

Lovable.dev is a powerful platform for generating full-stack web apps from natural language prompts. However, the speed of "vibe coding" can lead to security oversights. A Lovable.dev data leak typically happens because the AI-generated code includes hardcoded secrets, misconfigured environment variables, or overly open database rules. This article walks you through the most common data leak vectors in Lovable.dev apps and shows you exactly how to test and fix them.

Common Lovable.dev Data Leaks

1. Exposed API Keys and Secrets

Lovable apps often use Supabase, Stripe, or other third-party services. If you or the AI placed API keys directly in client-side code or committed them to public repositories, attackers can steal those keys and access your user data.

How to check:

  • •Open your app in a browser and press F12 to open DevTools.
  • •Go to the Network tab and reload the page.
  • •Look for requests to your backend or third-party services. Click on any request and inspect the Request Headers or Payload for hardcoded keys like supabaseKey, stripe_sk_live, or api_key.
  • •Also check the Sources tab for JavaScript files. Search for "sk_live", "pk_live", "supabase", or "service_role".

    • Fix:

  • •Move all secrets to environment variables (.env.local for local development, and set them in your hosting provider's dashboard).
  • •Never prefix environment variables with NEXT_PUBLIC_ or REACT_APP_ unless they are meant to be public (e.g., Stripe publishable key).
  • •Rotate any leaked keys immediately.

    • 2. Missing Authentication on API Routes

    Lovable generates routes quickly, but it often forgets to add authentication checks. If your /api/users endpoint returns all user data without a token check, anyone can steal your entire user database.

    How to check:

  • •With DevTools open, try to access API endpoints directly in a new tab. For example, if your app uses /api/users, navigate to https://your-app.com/api/users.
  • •If you see JSON data (especially with fields like email, passwordHash, address), your app is leaking data.
  • •Also test endpoints like /api/admin, /api/export, or /api/config.

    • Fix:

  • •Add middleware or authentication checks to every API route. In Next.js, use getServerSession() or a similar function to verify the user's identity.
  • •For Supabase, use Row Level Security (RLS) policies to restrict data access. Never allow public read access to user tables.

    • 3. Permissive CORS Policies

    Lovable apps often set Access-Control-Allow-Origin: * during development and forget to lock it down. This allows any website to make requests to your API and read responses.

    How to check:

  • •In the Network tab, find a request to your backend and look at the Response Headers.
  • •If you see Access-Control-Allow-Origin: *, your app is vulnerable.

    • Fix:

  • •Set the CORS origin to your specific frontend domain in production. For example, in a Node.js backend:

    • ```javascript

    app.use(cors({ origin: 'https://your-app.com' }));

    ```

  • •If using Supabase, restrict CORS in the Supabase dashboard under Settings > API.

    • 4. Verbose Error Messages

    Lovable-generated error handlers sometimes return full stack traces or SQL queries to the client. This can reveal database schema, table names, and even user data.

    How to check:

  • •Trigger an error intentionally. For example, try logging in with an invalid email format or sending a malformed request.
  • •Check if the error response includes stack traces, SQL queries, or internal file paths.

    • Fix:

  • •In production, always return generic error messages like "Internal server error" or "Invalid input."
  • •Log detailed errors to a server-side logger (e.g., Sentry) but never send them to the client.

    • 5. Exposed Environment Variables via Client-Side Bundles

    If you use process.env.NEXT_PUBLIC_SUPABASE_SERVICE_ROLE_KEY (with NEXT_PUBLIC_), that key is bundled into client-side JavaScript. Anyone can view it by searching the Sources tab.

    How to check:

  • •In DevTools Sources tab, open the main JavaScript bundle (usually _next/static/chunks/pages/...).
  • •Search for "SERVICE_ROLE" or "SUPABASE_KEY". If you find it, attackers can use that key to bypass RLS and access all data.

    • Fix:

  • •Never expose service_role keys to the client. Use anon keys with proper RLS policies.
  • •For other secrets, use server-only environment variables (no NEXT_PUBLIC_ prefix).

    • Step-by-Step: How to Test Your Lovable.dev App for Data Leaks

  • Open your app in an incognito window (to simulate an unauthenticated user).
  • Open DevTools (F12) and go to the Network tab.
  • Refresh the page and look for API calls. Click on each one and inspect:

    • - Request headers (for hardcoded keys)

    - Response body (for user data returned without auth)

    - Response headers (for CORS policy)

  • Check the Sources tab for hardcoded secrets in JS files.
  • Test API endpoints directly by typing URLs like /api/users, /api/admin, /api/config.
  • Trigger errors and inspect error messages for stack traces.
  • Check your public repository (if any) for committed .env files or secrets.

    • If you find any of these issues, fix them immediately and rotate any exposed keys.

    How OverMCP Can Help

    Manually checking for leaks is tedious, especially if you have multiple endpoints. OverMCP automates security scanning for vibe-coded apps, including Lovable.dev projects. It checks for exposed secrets, misconfigured CORS, missing authentication, and more—all with a single scan. OverMCP integrates directly into your CI/CD pipeline and alerts you before you deploy a leaky app.

    FAQ

    How do I know if my Lovable.dev API keys are exposed?

    Open your app, press F12, go to the Network tab, and look for any requests that include supabaseKey, service_role, or sk_live in the request headers or payload. Also check the Sources tab for hardcoded secrets in JavaScript files.

    Can a Lovable.dev data leak lead to a full account takeover?

    Yes. If an attacker obtains your Supabase service_role key or a Stripe secret key, they can read all user data, delete records, or even make unauthorized charges. Always use least-privilege keys and rotate them regularly.

    What is the fastest way to secure my Lovable.dev app?

    Run a security scan with a tool like OverMCP, fix any high-severity issues (exposed keys, missing auth, permissive CORS), enable RLS on your database, and set environment variables correctly. This usually takes less than 30 minutes.

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