Lovable security

CORS Misconfiguration in Lovable App

Your Lovable app either blocks legitimate requests with CORS errors or is configured with overly permissive CORS settings (Access-Control-Allow-Origin: *) that allow any website to make requests to your API.

CORS errors appear as failed API calls in the browser console, preventing your app from communicating with its backend or third-party services. On the other hand, wildcard CORS settings mean any malicious website could make requests to your API on behalf of your users.

This commonly happens when your frontend and backend are on different domains, or when Lovable generates API routes without proper CORS configuration.

Error Messages You Might See

Access to fetch at 'https://api...' has been blocked by CORS policy No 'Access-Control-Allow-Origin' header is present on the requested resource CORS policy: Response to preflight request doesn't pass access control check The value of the 'Access-Control-Allow-Origin' header must not be the wildcard '*' when the request's credentials mode is 'include'
Access to fetch at 'https://api...' has been blocked by CORS policyNo 'Access-Control-Allow-Origin' header is present on the requested resourceCORS policy: Response to preflight request doesn't pass access control checkThe value of the 'Access-Control-Allow-Origin' header must not be the wildcard '*' when the request's credentials mode is 'include'

Common Causes

  • Wildcard origin allowed — The API is configured with Access-Control-Allow-Origin: * which is insecure for authenticated endpoints
  • Missing CORS headers — The backend doesn't include the necessary CORS headers, blocking frontend requests
  • Credentials with wildcard — Trying to send cookies/auth headers with a wildcard CORS policy, which browsers block
  • Preflight request failing — OPTIONS requests are not handled, causing complex requests (POST with JSON) to fail
  • Different domains in production — Frontend and API are on different domains but CORS is only configured for localhost

How to Fix It

  1. Set specific allowed origins — Replace wildcard (*) with your actual frontend domain(s)
  2. Handle OPTIONS preflight — Make sure your server responds to OPTIONS requests with proper CORS headers
  3. Allow credentials properly — If using cookies/auth, set Access-Control-Allow-Credentials: true with a specific origin (not wildcard)
  4. Configure allowed methods and headers — Explicitly list the HTTP methods and headers your frontend needs
  5. Test with browser DevTools — Check the Network tab for failed preflight requests and missing headers

Real developers can help you.

Nam Tran Nam Tran 10 years as fullstack developer Luca Liberati Luca Liberati I work on monoliths and microservices, backends and frontends, manage K8s clusters and love to design apps architecture Milan Surelia Milan Surelia Milan Surelia is a Mobile App Developer with 5+ years of experience crafting scalable, cross-platform apps at 7Span and Meticha. At 7Span, he engineers feature-rich Flutter apps with smooth performance and modern UI. As the Co-Founder of Meticha, he builds open-source tools and developer-focused products that solve real-world problems. Expertise: 💡 Developing cross-platform apps using Flutter, Dart, and Jetpack Compose for Android, iOS, and Web. 🖋️ Sharing insights through technical writing, blogging, and open-source contributions. 🤝 Collaborating closely with designers, PMs, and developers to build seamless mobile experiences. Notable Achievements: 🎯 Revamped the Vepaar app into Vepaar Store & CRM with a 2x performance boost and smoother UX. 🚀 Launched Compose101 — a Jetpack Compose starter kit to speed up Android development. 🌟 Open source contributions on Github & StackOverflow for Flutter & Dart 🎖️ Worked on improving app performance and user experience with smart solutions. Milan is always happy to connect, work on new ideas, and explore the latest in technology. Matthew Butler Matthew Butler Systems Development Engineer @ Amazon Web Services Yovel Cohen Yovel Cohen I got a lot of experience in building Long-horizon AI Agents in production, Backend apps that scale to millions of users and frontend knowledge as well. BurnHavoc BurnHavoc Been around fixing other peoples code for 20 years. David Olverson David Olverson Solo dev shipping production apps with AI-assisted development. I specialize in rescuing broken Lovable/Bolt/Cursor builds and taking them to production. 10+ apps shipped including SaaS CRMs, gaming platforms, real estate tools, and Discord bots. Stack: Next.js 16, TypeScript, Tailwind CSS, FastAPI, PostgreSQL, Prisma. I use Claude Code with 50+ custom skills for rapid delivery. Average turnaround: 2-4 weeks from broken prototype to production. Rudra Bhikadiya Rudra Bhikadiya I build and fix web apps across Next.js, Node.js, and DBs. Comfortable jumping into messy code, broken APIs, and mysterious bugs. If your project works in theory but not in reality, I help close that gap. Simon A. Simon A. I'm a backend developer building APIs, emulators, and interactive game systems. Professionally, I've developed Java/Spring reporting solutions, managed relational and NoSQL databases, and implemented CI/CD workflows. hanson1014 hanson1014 Full-stack developer experienced in fixing and deploying AI-generated apps from Lovable, Bolt.new, Cursor, and Replit. I specialize in debugging Supabase integration issues (auth flows, RLS policies, database connections), fixing broken deployments, resolving routing/blank screen problems, and cleaning up messy React/Vite codebases. I also build production apps with the Claude API and have shipped a Mac desktop dev tool (Nexterm from scratch. Based in Hong Kong, fast turnaround.

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Frequently Asked Questions

What is CORS and why does it exist?

CORS (Cross-Origin Resource Sharing) is a browser security feature that prevents websites from making requests to a different domain than the one that served the page. It protects users from malicious sites making unauthorized API calls.

Is it safe to use Access-Control-Allow-Origin: * ?

Only for public APIs that don't use authentication. For any API that handles user data or requires login, you must specify exact allowed origins.

Related Lovable Issues

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