templates
Access Control templates
How Supabase data access is enforced (or accidentally bypassed) through RLS, grants, and backend-only patterns. This page collects practical templates and explains how this category fails in real Supabase apps — plus the safest fix patterns to apply.
What Access Control means for Supabase security
Access control in Supabase is a combination of Postgres grants, Row Level Security (RLS), and how your app routes requests. The safest default is backend-only access: the browser never talks to tables, RPC, or storage directly.
Access Control templates in this library
| Template | Best for | URL |
|---|---|---|
| Lock down a public table (backend-only access) | A template to revoke direct client access, enable RLS, remove policies, and force all reads/writes through your backend using service_role. | /templates/access-control/lock-down-public-table |
| Remove over-permissive RLS policies (adopt deny-by-default) | A template to remove broad policies that leak data and move to a backend-only, deny-by-default posture that is easier to reason about and verify. | /templates/access-control/remove-over-permissive-policies |
How Access Control fails in real apps
- Relying on “logged in” as authorization (authenticated ≠ authorized).
- Assuming policies work when RLS is disabled.
- Using broad conditions that don’t bind rows to a user/tenant.
- Fixing one table but leaving storage/RPC exposed.
How to fix Access Control issues safely
- Start by removing direct client access to sensitive resources.
- Centralize authorization in backend endpoints.
- Use RLS as an additional safety gate (not the only one).
- Verify fixes with direct access tests and re-scans.
Verification checklist for Access Control fixes
- Identify the exact surface you’re changing (table, bucket, function).
- Apply the template and keep a rollback path (feature flag or staged rollout) if possible.
- Attempt direct access using client credentials (it should fail after the fix).
- Confirm the app still works via backend endpoints for authorized users.
- Re-run a scan and re-run any SQL checklist queries you use for drift detection.
Common pitfalls when applying Access Control templates
- Treating policies as the only control instead of also removing direct client paths.
- Forgetting to repeat the same hardening steps in production (drift between environments).
- Locking down reads but leaving writes exposed (or vice versa).
- Fixing the database but leaving Storage/RPC surfaces publicly accessible.
- Skipping verification and assuming “the UI works” means “it’s secure.”
Related glossary terms
- Row Level Security (RLS) →
/glossary/row-level-security - Public Table Exposure →
/glossary/public-table-exposure - Over-permissive RLS Policies →
/glossary/over-permissive-rls-policies
How Access Control connects to conversions and examples
If you need the “full story” (not just copy/paste SQL), use these cross-playbook links:
- Conversions explain the entire unsafe → safe transformation and reduce missed steps.
- Examples show how the exposure shipped and how to verify your fix is real.
Use sibling category pages to broaden coverage, then return to the templates to apply changes with verification.
How to adapt Access Control templates to your schema
- Replace table/bucket/function names carefully and double-check you didn’t widen access accidentally.
- If you have multi-tenant data, make sure every rule binds rows to a tenant boundary (not just “logged in”).
- Prefer smaller, verifiable changes over large refactors; ship one fix, verify, then repeat.
- After applying a template, re-run the same direct access test you used to validate the risk.
Quick validation questions for Access Control
Use these questions to confirm you picked the right category and template before you make breaking changes:
- Can I access the resource directly without going through my backend?
- If I revoke client access, do I have a backend endpoint ready to replace it?
- Do I know how to prove the fix worked (one direct access test)?
- Am I fixing all environments (dev/staging/prod) or only one?
Next steps
Pick one template, apply it in staging, and run the verification checklist.
Then re-scan so you catch drift before it becomes an incident.
FAQ
What’s the fastest Access Control improvement with the highest impact?
Remove direct client access to sensitive resources and route reads/writes through a backend layer. This reduces exposure even when policies are imperfect.
Do I have to use every template in Access Control?
No. Choose templates that match real, validated risks in your project. If you can’t validate a risk, don’t ship a disruptive change “just in case.”
How do I keep fixes from regressing?
Add a repeatable checklist (or automated checks) that runs after schema changes, and periodically re-scan production configuration.
Next step
If you want these templates to match your exact schema and exposure, scan your project in Mockly and follow the linked fixes.