Common Issues auth

Users Can See Each Other's Private Data

Users in your app can see data that belongs to other users — viewing other people's orders, messages, personal information, or account details. This is a serious privacy and security issue that needs to be fixed immediately.

Common Causes

  • No Row Level Security (RLS) — database queries return all data, not just the current user's
  • API endpoints don't filter data by the authenticated user's ID
  • User ID taken from the request body instead of the authenticated session
  • Shared cache serving one user's data to another
  • Query fetches all records and filters on the frontend only

How to Fix It

  1. This is urgent — fix it before anything else. Consider taking the affected features offline temporarily.
  2. Check every API endpoint that returns user data — make sure it filters by the authenticated user's ID
  3. If using Supabase, implement RLS policies on all tables containing user data
  4. Never trust user ID from the request body — always get it from the server-side session
  5. Test by logging in as different users and verifying each only sees their own data

Real developers can help you.

Mehdi Ben Haddou Mehdi Ben Haddou - Founder of Chessigma (1M+ users) & many small projects - ex Founding Engineer @Uplane (YC F25) - ex Software Engineer @Amazon and @Booking.com Alvin Voo Alvin Voo I’ve watched the tech landscape evolve over the last decade—from the structured days of Java Server Pages to the current "wild west" of Agentic-driven development. While AI can "vibe" a frontend into existence, I specialize in the architecture that keeps it from collapsing. My expertise lies in the critical backend infrastructure: the parts that must be fast, secure, and scalable. I thrive on high-pressure environments, such as when I had only three weeks to architect and launch an Ethereum redemption system with minimal prior crypto knowledge, turning it into a major revenue stream. What I bring to your project: Forensic Debugging: I don't just "patch" bugs; I use tools like Datadog and Explain Analyzers to map out bottlenecks and resolve root causes—like significantly reducing memory usage by optimizing complex DB joins. Full-Stack Context: Deep experience in Node.js and React, ensuring backends play perfectly with mobile and web teams. Sanity in the Age of AI: I bridge the gap between "best practices" and modern speed, ensuring your project isn't just built fast, but built to last. Meïr Ankri Meïr Ankri Full-stack developer specializing in React / Next.js / Node.js with 6+ years of experience. I've worked across various sectors including automotive (Reezocar/Société Générale), healthcare (Medical Link SaaS), and e-commerce (Glasman). I build web apps end-to-end, from architecture to production, with a focus on scalability, performance, and code quality. I also mentor junior developers and contribute to technical decisions and code reviews. Costea Adrian Costea Adrian Embedded Engineer specilizing in perception systems. Latest project was a adas camera calibration system. Richard McSorley Richard McSorley Full-Stack Software Engineer with 8+ years building high-performance applications for enterprise clients. Shipped production systems at Walmart (4,000+ stores), Cigna (20M+ users), and Arkansas Blue Cross. 5 patents in retail/supply chain tech. Currently focused on AI integrations, automation tools, and TypeScript-first architectures. Anthony Akpan Anthony Akpan Developer with 8 years of experience building softwares fro startups Dor Yaloz Dor Yaloz SW engineer with 6+ years of experience, I worked with React/Node/Python did projects with React+Capacitor.js for ios Supabase expert Franck Plazanet Franck Plazanet I am a Strategic Engineering Leader with over 8 years of experience building high-availability enterprise systems and scaling high-performing technical teams. My focus is on bridging the gap between complex technology and business growth. Core Expertise: 🚀 Leadership: Managing and coaching teams of 15+ engineers, fostering a culture of accountability and continuous improvement. 🏗️ Architecture: Enterprise Core Systems, Multi-system Integration (ERP/API/ETL), and Core Database Structure. ☁️ Cloud & Scale: AWS Expert; architected systems handling 10B+ monthly requests and managing 100k+ SKUs. 📈 Business Impact: Aligning tech strategy with P&L goals to drive $70k+ in monthly recurring revenue. I thrive on "out-of-the-box" thinking to solve complex technical bottlenecks and am always looking for ways to use automation to improve business productivity. Kingsley Omage Kingsley Omage Fullstack software engineer passionate about AI Agents, blockchain, LLMs. Luca Liberati Luca Liberati I work on monoliths and microservices, backends and frontends, manage K8s clusters and love to design apps architecture

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Frequently Asked Questions

How serious is this?

Very serious. This is a data privacy violation that could have legal consequences (GDPR, etc.). Fix it immediately and consider notifying affected users if sensitive data was exposed.

Can this be fixed without rebuilding the app?

Yes. Adding proper RLS policies (for Supabase) or API-level authorization checks can fix this without a rebuild. A developer can usually fix it within a day.

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