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 marketplace data, create records, or inspect a public bundle and find Supabase keys sitting in the browser. In a Lovable plus Supabase MVP, the most likely root cause is that the product was shipped with client-side access patterns and no real row-level security or auth gate around sensitive actions.

The first thing I would inspect is not the UI. I would inspect the deployed frontend bundle, Supabase auth settings, and every table policy before touching code. If auth is missing, I treat it as a production incident because the business risk is direct: data exposure, fake listings, spam orders, support load, and a launch delay while you rebuild trust.

Triage in the First Hour

1. Check the live site in an incognito window.

• Can I view protected pages without signing in?
• Can I create or edit marketplace records without a session?

2. Inspect browser network calls.

• Look for direct Supabase requests from the client.
• Confirm whether any key in the frontend is a public anon key or something worse.

3. Review Supabase Auth dashboard.

• Is email auth enabled?
• Are sign-up and sign-in flows actually wired?
• Are redirect URLs correct for production?

4. Open the database policies.

• Check every table used by listings, orders, messages, profiles, and admin actions.
• Look for missing RLS or policies that allow broad `select`, `insert`, `update`, or `delete`.

5. Review storage buckets.

• Are uploads public by default?
• Can anyone list or download private files?

6. Inspect environment variables in Lovable and hosting.

• Confirm secrets are not hardcoded into components.
• Check preview and production environments separately.

7. Review recent deploys and build output.

• Did a merge expose `.env` values into client code?
• Did a generated component bypass your auth wrapper?

8. Check logs for suspicious activity.

• Sudden spikes in anonymous writes.
• Repeated failed auth attempts.
• Unusual reads from marketplace tables.

A quick diagnostic command I would run locally:

grep -R "supabase" src . | head -50

I am looking for direct client usage patterns, hardcoded keys, and places where sensitive operations are happening without an auth check.

Root Causes

| Likely cause | What it looks like | How I confirm it | |---|---|---| | Public key confusion | A key is visible in frontend code and someone thinks it is secret | Check whether it is the Supabase anon key or a true service role key | | Missing RLS | Tables are readable or writable by anyone with the anon client | Query policies in Supabase and test from an unsigned session | | Auth not enforced in UI only | Pages look gated but API routes still accept requests | Call the underlying endpoints directly from an unauthenticated session | | Service role key leaked | Admin-level access was bundled into frontend code or shared config | Search build artifacts and hosting env vars for service role usage | | Over-permissive storage | Files can be uploaded or fetched without ownership checks | Test bucket permissions and object path access rules | | Generated app drift | Lovable generated screens after auth was added, but new flows skipped guards | Compare recent generated components to protected routes and forms |

The biggest mistake here is assuming "the page is hidden" equals "the data is protected." It does not. In marketplace products, the backend must enforce ownership rules even if every UI screen looks locked down.

The Fix Plan

I would fix this in layers so we stop exposure first, then restore proper access control, then redeploy safely.

1. Rotate anything exposed.

• If there is any chance a service role key leaked, rotate it immediately.
• Regenerate tokens, update secrets stores, and invalidate old credentials where possible.

2. Remove secrets from client code.

• Move all privileged keys to server-only environment variables.
• Keep only the Supabase anon key on the client if needed for authenticated public access.

3. Turn on Row Level Security everywhere sensitive data exists.

• Listings
• Orders
• Messages
• Profiles
• Payout data
• Admin-only tables

4. Write policies based on ownership and role.

• Users can read their own records.
• Sellers can manage only their own listings.
• Buyers can see only their own orders and messages.
• Admin actions require explicit admin claims or server-side checks.

5. Move privileged operations behind server-side endpoints.

• Stripe webhooks
• payout creation
• moderation actions
• admin edits
• invite flows

6. Add auth guards at both layers.

• Frontend route protection for user experience
• Backend authorization for actual security

7. Lock down storage buckets.

• Private by default for user uploads
• Signed URLs for controlled access
• Ownership checks on upload paths

8. Fix production deployment hygiene.

• Separate preview and prod env vars
• Verify Cloudflare caching does not cache private responses
• Ensure redirects preserve login flow

9. Add monitoring before relaunching traffic.

• Auth failure alerts
• unusual write spikes

- unexpected policy denials - uptime checks on critical pages

If I were doing this as Launch Ready work, I would keep the scope tight: secure what exists first instead of redesigning features while data exposure is still possible.

Regression Tests Before Redeploy

Before shipping, I want proof that unauthorized users cannot read or write anything sensitive.

• Anonymous user cannot access protected pages beyond marketing content.
• Anonymous user cannot create listings, messages, orders, or profile updates.
• Logged-in buyer cannot edit another seller's listing.
• Logged-in seller cannot read another seller's private data unless explicitly allowed.
• Storage upload rejects unauthorized file paths.
• Admin-only actions fail for non-admin sessions.
• Public pages still load normally after caching changes.

Acceptance criteria I would use:

• 100 percent of sensitive tables have RLS enabled.
• Zero service role keys exist in client bundles or browser-visible config.
• Protected API routes return `401` or `403` when unauthenticated or unauthorized.
• Lighthouse performance stays above 85 on core public pages after security changes.
• No regression in signup completion rate below 90 percent of baseline during QA.

I also want one realistic manual test pass on mobile because marketplace MVPs often break there first. If login redirects fail on iPhone Safari, you will lose signups even if security is fixed.

Prevention

This issue comes back when teams ship fast without guardrails. I would put these controls in place immediately after repair.

• Security review before every deploy:
• Check RLS coverage
• Check env var scope

- confirm no secret reaches client code

• Code review rules:

- no direct writes to sensitive tables from unauthenticated components - no admin logic inside frontend-only files

• Logging:

- log auth failures without leaking tokens or PII - alert on repeated unauthorized writes

• Monitoring:

- uptime checks on login, listing creation, checkout, and dashboard pages - error tracking on permission denials versus real crashes

• UX guardrails:

- clear login states - empty states that explain why content is hidden - visible error messages when permission fails

• Performance guardrails:

- do not cache private responses at Cloudflare edge - keep protected queries indexed so auth checks do not slow p95 over 300 ms

For marketplaces specifically, I recommend treating authorization as part of conversion work. If users hit confusing permission errors after signup, they churn just as fast as they do when they get hacked out of their account.

When to Use Launch Ready

Use Launch Ready when you have a working Lovable plus Supabase MVP that needs to be made safe enough to ship publicly within 48 hours.

It fits best when you need:

• domain setup and DNS cleanup,
• email deliverability with SPF/DKIM/DMARC,
• Cloudflare protection,
• SSL,
• deployment cleanup,
• secrets handling,
• uptime monitoring,
• handover documentation,
• one focused security rescue sprint before launch ads go live.

That makes sense when the alternative is delaying launch by one to two weeks while trying to patch security piecemeal across different freelancers.

What I need from you before starting:

• Supabase project access with admin rights,
• hosting access,
• domain registrar access,
• Cloudflare access if already connected,
• current build link,
• list of roles: buyer, seller, admin,
• examples of tables involved in listings and orders,
• any existing auth flow notes or screenshots.

If you are unsure whether your issue is "just" exposed keys or a deeper access-control problem, assume it is deeper until proven otherwise. That assumption saves money because it prevents a second incident after you patch only the visible leak.

References

1. roadmap.sh API Security Best Practices: https://roadmap.sh/api-security-best-practices 2. roadmap.sh Cyber Security: https://roadmap.sh/cyber-security 3. Supabase Security Overview: https://supabase.com/docs/guides/platform/security 4. Supabase Row Level Security: https://supabase.com/docs/guides/database/postgres/row-level-security 5. Cloudflare Security Docs: https://developers.cloudflare.com/fundamentals/security/

---

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.*