How I Would Fix exposed API keys and missing auth in a Lovable plus Supabase marketplace MVP Using Launch Ready.

How I Would Fix exposed API keys and missing auth in a Lovable plus Supabase marketplace MVP Using Launch Ready

The symptom is usually obvious: the app works, but anyone can hit sensitive endpoints, create listings, read data they should not see, or reuse a key that was accidentally shipped to the browser. In a Lovable plus Supabase marketplace MVP, the most likely root cause is that the app was built fast with public-facing variables, weak Row Level Security, and no real server-side gate around write actions.

The first thing I would inspect is whether any secret is actually exposed in the client bundle or network calls, then I would check Supabase auth state and table policies before touching UI code. If auth is missing or broken at the data layer, redesigning screens will not fix the business risk: exposed customer data, fake listings, support load, and a launch that can get shut down by abuse.

Triage in the First Hour

1. Check the live site in an incognito window.

• Try browsing marketplace pages without signing in.
• Try creating, editing, or deleting a listing from the UI.
• Confirm whether private data loads before login.

2. Inspect browser devtools.

• Open Network and look for direct calls to Supabase tables or functions.
• Check if any API key appears in JS bundles, request headers, or source maps.
• Verify whether requests are using anon keys only or anything that should be private.

3. Review Supabase Auth dashboard.

• Confirm sign-up, sign-in, password reset, and email verification status.
• Check if users are being created correctly and whether sessions persist.
• Look for suspicious spikes in signups or failed logins.

4. Audit database policies first.

• Review Row Level Security on every table with user-generated content.
• Check whether policies are missing, too broad, or accidentally disabled.
• Verify storage bucket access if images or files are part of listings.

5. Review environment variables in Lovable and deployment settings.

• Confirm what is set in build time versus runtime.
• Make sure service role keys are not present in client-side variables.
• Check whether preview deployments share production secrets.

6. Inspect logs and monitoring.

• Look for unauthorized writes, repeated 401/403s, and abnormal traffic.
• Review Supabase logs for direct table access without auth context.
• Check uptime alerts and error rates before making changes.

7. Freeze risky changes.

• Pause new feature work for 24 to 48 hours.
• Stop any ad spend until auth and data exposure are confirmed fixed.
• Take a backup of schema, policies, and current deploy state.

## Quick audit helpers
supabase db diff
supabase secrets list
supabase gen types typescript --project-id YOUR_PROJECT_ID

Root Causes

| Likely cause | What it looks like | How I confirm it | |---|---|---| | Missing Row Level Security | Any logged-out user can read or write rows | Check table settings in Supabase; if RLS is off on user data tables, that is the problem | | Overly broad policies | Users can see all marketplace records | Review policy SQL for `true`, `auth.role() = 'authenticated'` without ownership checks, or wildcard access | | Secrets shipped to client | Private key appears in bundle or browser requests | Search build output and source maps for `service_role`, API tokens, or private URLs | | Client-side writes without server checks | Anyone can call create/update endpoints directly | Test endpoints from devtools or curl with no session; if writes still succeed, auth is missing | | Broken auth wiring in Lovable | UI shows login but backend ignores it | Compare frontend session state with actual Supabase user ID used in queries | | Storage bucket misconfig | Anyone can upload or fetch private images | Inspect bucket policies and test access to file URLs without signing in |

The Fix Plan

My rule here is simple: fix authorization at the data layer first, then clean up the UI. If you only hide buttons in the frontend, you still have an open marketplace backend that can be scraped or abused.

1. Rotate exposed secrets immediately.

• Revoke any leaked API keys right away.
• Replace them everywhere they were used: Supabase dashboard, deployment platform, CI/CD secrets manager, and local `.env`.
• If a service role key was exposed publicly, treat it as compromised until rotated.

2. Separate public from private keys correctly.

• Public anon keys can exist in the browser if RLS is strict.
• Service role keys must stay server-only and never ship to Lovable client code.
• Move privileged operations behind server actions, edge functions, or backend routes.

3. Turn on RLS for every sensitive table.

• Enable RLS on listings that are user-owned or moderation-controlled.
• Write policies for `select`, `insert`, `update`, and `delete` separately.
• Use ownership checks like `auth.uid() = user_id` instead of broad authenticated access.

4. Lock down storage buckets too.

• Make private assets private by default.
• Use signed URLs where needed for uploads or downloads.
• Prevent anonymous file listing if marketplace media contains sensitive content.

5. Add server-side validation for writes.

• Validate listing fields on insert: title length, price range, category enum, image count limits.
• Reject requests that do not have a valid session identity attached to them.
• Do not trust hidden form fields from the client.

6. Fix auth flows end to end.

• Require email verification if your marketplace depends on trusted accounts.
• Add clear login redirects for protected actions like posting a listing or messaging sellers.
• Make sure session refresh works after deployment so users do not get random logouts.

7. Clean up deployment hygiene.

• Put production secrets only in production environment variables.
• Remove secrets from preview branches unless they are intentionally scoped test values.
• Confirm Cloudflare caching does not cache private pages or authenticated responses.

8. Add basic monitoring before re-opening traffic.

• Alert on unusual insert volume, repeated failed logins, and policy violations.
• Track 401s and 403s separately so you can tell broken auth from blocked abuse.
• Set uptime checks on homepage plus core marketplace actions.

If I were rescuing this as Launch Ready work, I would keep the repair narrow: one security sprint focused on exposure removal first, then one pass on UX cleanup after access control is proven correct. That avoids turning a security incident into a full rebuild.

Regression Tests Before Redeploy

I would not redeploy until these checks pass:

• Anonymous access tests
• Log out completely and verify protected routes redirect to login or show safe public-only content.
• Try direct API calls without a session; writes must fail with 401 or 403.

• Ownership tests
• User A cannot edit User B's listings or messages.
• User A cannot view private drafts belonging to User B.

• Storage tests
• Private images cannot be fetched by guessing their URL alone unless signed access is valid.

• Auth flow tests
• Sign up works end to end with email verification if enabled.
• Password reset completes without breaking session handling.

• Secret handling tests
• Search deployed JS bundles for service role keys and private tokens; none should be present.
• Confirm environment variables differ between local preview and production where needed.

• Marketplace behavior tests
• Create listing flow succeeds only when authenticated and validated fields are correct.
• Search results still work publicly if intended but do not leak private owner data.

• Security acceptance criteria
• All sensitive tables have RLS enabled with explicit policies documented per table.
• No privileged operation runs from client-only code paths.

``` Acceptance target: RLS enabled on 100 percent of sensitive tables Exposed secret count: 0 Unauthorized write attempts: blocked at least 10 out of 10 test cases ```

Prevention

I would put guardrails around this so it does not come back two weeks later when someone ships another quick change from Lovable.

• Security review gate
• Any change touching auth, storage, roles, webhooks, or database policies needs review before merge or publish:

one engineer checks behavior, one checks permissions, one checks secret handling.

• Policy-as-code mindset
• Keep RLS SQL under version control alongside app code where possible。

- Document every table policy so future edits do not silently open access again.

• Secret scanning

- Use secret scanning in GitHub plus deployment logs so leaked keys get caught early。

• Monitoring guardrails

- Alert on spikes in anonymous requests, failed writes, new account bursts, and unexpected data exports。

• UX guardrails

- Make protected actions obviously gated: "Sign in to post", "Verify email to message sellers", "Complete profile before publishing"。

This reduces confusion-driven support tickets and stops users from thinking broken permissions are just bad UX。

• Performance guardrails

- Do not add heavy client-side authorization logic that duplicates backend checks。

Keep public pages fast, but never trade speed for weak access control。

When to Use Launch Ready

Launch Ready fits when you need me to stop the bleeding fast without turning your MVP into a six-week rebuild. I handle domain setup, email, Cloudflare, SSL, deployment, secrets, and monitoring, which is exactly what you need when an AI-built app has outgrown its prototype setup。

What I include:

• DNS setup and redirects
• Subdomains if needed
• Cloudflare protection and caching rules
• SSL setup
• DDoS protection basics
• SPF,

DKIM, and DMARC for email deliverability

• Production deployment review
• Environment variable cleanup
• Secrets handling check
• Uptime monitoring
• Handover checklist

What you should prepare:

• Access to Lovable project settings
• Supabase admin access
• Domain registrar login
• Cloudflare account if already connected
• Deployment platform access such as Vercel,

Netlify, or similar

If your issue includes exposed keys plus missing auth, I would usually split the work into two decisions: 1) secure production now so traffic stops leaking data; 2) then schedule a follow-up sprint for proper role design, moderation flows, and marketplace UX improvements。

That path is cheaper than waiting until users report abuse after launch。

References

• https://roadmap.sh/api-security-best-practices
• https://roadmap.sh/cyber-security
• https://roadmap.sh/code-review-best-practices
• https://supabase.com/docs/guides/database/postgres/row-level-security
• https://supabase.com/docs/guides/auth

---

Take the next step

If this is a problem in your product right now, here is what to do next:

• [Use the free Cyprian tools](/tools) - estimate cost, score app risk, check launch readiness, or pick the right service sprint.

• [Book a discovery call](/contact) - I will tell you honestly whether you need a sprint or if you can DIY the next step.

*Written by Cyprian Tinashe Aarons - senior full-stack and AI engineer helping founders rescue, launch, automate, and scale AI-built products.*