8 Security Mistakes That Can Hack Your SaaS
The biggest problem with 𝘃𝗶𝗯𝗲 𝗰𝗼𝗱𝗶𝗻𝗴 isn't speed. It's 𝘀𝗲𝗰𝘂𝗿𝗶𝘁𝘆. (And here's how to fix it in 𝟴 𝘀𝘁𝗲𝗽𝘀) Last month, a builder launched their SaaS. Within 24 hours: → Bots hit their signup endpoint 10,000 times → Database crashed → $300 in Supabase costs All because they shipped fast but forgot security. --- 𝗧𝗵𝗲 𝗽𝗿𝗼𝗯𝗹𝗲𝗺 𝘄𝗶𝘁𝗵 𝘃𝗶𝗯𝗲 𝗰𝗼𝗱𝗶𝗻𝗴: Your MVP works great in development. But launch day is when the real world finds your weak spots. Cursor moves fast. Security doesn't come built-in. --- 𝗛𝗲𝗿𝗲'𝘀 𝘁𝗵𝗲 𝟴-𝘀𝘁𝗲𝗽 𝗹𝗮𝘂𝗻𝗰𝗵 𝗰𝗵𝗲𝗰𝗸𝗹𝗶𝘀𝘁: 𝟭. 𝗥𝗮𝘁𝗲 𝗹𝗶𝗺𝗶𝘁 𝘆𝗼𝘂𝗿 𝗲𝗻𝗱𝗽𝗼𝗶𝗻𝘁𝘀 → Supabase Edge Functions + rate limiter → Vercel Middleware → Next.js IP throttling Skip this = bots hit you 100x/second. 𝟮. 𝗘𝗻𝗮𝗯𝗹𝗲 𝗥𝗼𝘄-𝗟𝗲𝘃𝗲𝗹 𝗦𝗲𝗰𝘂𝗿𝗶𝘁𝘆 (𝗥𝗟𝗦) → Turn on RLS on every Supabase table → Use policies: user_id = auth.uid() No RLS = users can query other people's data. 𝟯. 𝗔𝗱𝗱 𝗖𝗔𝗣𝗧𝗖𝗛𝗔 𝘁𝗼 𝗮𝘂𝘁𝗵 𝗳𝗹𝗼𝘄𝘀 → Signup forms → Login pages → Forgot password AI bots can generate 1000s of fake signups in minutes. 𝟰. 𝗘𝗻𝗮𝗯𝗹𝗲 𝗪𝗔𝗙 (𝗪𝗲𝗯 𝗔𝗽𝗽𝗹𝗶𝗰𝗮𝘁𝗶𝗼𝗻 𝗙𝗶𝗿𝗲𝘄𝗮𝗹𝗹) → Vercel → Settings → Security → WAF → Enable "Attack Challenge" on all routes 1 click. No code. Blocks bad traffic instantly. 𝟱. 𝗦𝗲𝗰𝘂𝗿𝗲 𝘆𝗼𝘂𝗿 𝗔𝗣𝗜 𝗸𝗲𝘆𝘀 → Store in .env files → Use server-only functions → Scan AI-generated code (it often forgets this) If it runs on the client, assume it's public. 𝟲. 𝗩𝗮𝗹𝗶𝗱𝗮𝘁𝗲 𝗮𝗹𝗹 𝗶𝗻𝗽𝘂𝘁𝘀 𝗼𝗻 𝘁𝗵𝗲 𝗯𝗮𝗰𝗸𝗲𝗻𝗱 → Emails, passwords, uploads → Custom form inputs → API payloads Don't trust the frontend. Ever. 𝟳. 𝗖𝗹𝗲𝗮𝗻 𝘂𝗽 𝗱𝗲𝗽𝗲𝗻𝗱𝗲𝗻𝗰𝗶𝗲𝘀 → Run npm audit fix → Remove unused packages → Check for critical vulnerabilities Cursor moves fast. It doesn't clean up after itself. 𝟴. 𝗔𝗱𝗱 𝗺𝗼𝗻𝗶𝘁𝗼𝗿𝗶𝗻𝗴 + 𝗹𝗼𝗴𝘀 → Supabase Logs → Vercel Analytics → Track failed logins, traffic spikes, 500s You can't fix what you can't see. --- 𝗕𝗼𝗻𝘂𝘀: 𝗔𝗜 𝗰𝗼𝗱𝗲 𝗿𝗲𝘃𝗶𝗲𝘄𝘀 Before you push, run CodeRabbit inside Cursor. It catches security flaws, performance issues, and bad logic. Like a senior dev reviewing your entire codebase. --- 𝗧𝗵𝗲 𝗯𝗼𝘁𝘁𝗼𝗺 𝗹𝗶𝗻𝗲: Cursor lets you code fast.