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A Supabase app can expose user data when its database permissions, Row Level Security (RLS), Storage policies, or privileged backend functions are too broad. A Supabase publishable key in browser code is expected; it is not a security policy. Use the checks below to look for obvious risks in your project, but treat ten minutes as triage—not proof that the app is secure. These are Supabase configuration risks that can affect an app built with Lovable; they do not establish that Lovable creates them by default.
What controls access in a Lovable + Supabase app?
Supabase Auth establishes who is signed in. Database grants and RLS policies determine what that identity can do with rows. Storage policies govern access to files, while privileged backend components may use credentials that bypass ordinary row-level checks.
A publishable key—sometimes called the legacy anon key—is designed to appear in a public frontend. It identifies the application; it does not identify an individual user or grant each user permission to every row. A secret key or legacy service-role key is different: it has elevated access and bypasses RLS, so it must stay in controlled server-side code. Supabase Docs, API keys and Row Level Security, accessed October 7, 2026, describe these distinctions.
So, “Is it safe that my Supabase key is in the frontend?” depends on which key it is. A publishable key can be public when grants and policies are deliberate. A secret or service-role key in browser code, a public repository, or logs is a serious exposure.
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Eight checks for data exposure
1. Find exposed tables without RLS
In each schema exposed through the API, identify every table—not only the table shown on the current page. If a table has no RLS, any role with a grant may be able to read or write it. Enable RLS and create policies that match the intended access. Supabase’s Row Level Security guidance explains the relationship between exposed tables, grants, and RLS.
2. Review grants and policies together
RLS policies do not remove SQL grants. Check both controls for each operation: SELECT, INSERT, UPDATE, and DELETE. Then test the intended allow and deny cases for both anon and authenticated roles. In particular, check whether one signed-in account can read or change another account’s rows.
Supabase recommends repeatable database tests for these cases. Its Row Level Security guide puts the assurance limit plainly: “Until the suite passes, you don’t know whether the policies do what you intended.”
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Inspect the repository, built JavaScript, environment-variable prefixes, and logs for credentials beginning with sb_secret_ or legacy service-role keys. A public environment-variable prefix or inclusion in a frontend bundle can expose its value to visitors. Publishable and legacy anon keys are intended for public use; secret and service-role keys bypass RLS.
If a privileged key was exposed, remove the exposure and rotate the credential using Supabase’s documented procedure. Do not paste a live credential into a public scanner or chat while checking.
4. Check bucket visibility and object policies
Review Storage bucket visibility and the policies on storage.objects, especially for user uploads and files meant to remain private. Supabase Storage uses RLS-based access policies, and service keys bypass those policies. Test both listing and fetching a supposedly private object while signed out and while signed in as a different ordinary user.
5. Do not confuse login with permission
A successful login proves identity; it does not grant access to every row. Check that policies rely on trusted identity and membership data. Do not use user-editable metadata as an authorization source: Supabase’s RLS guide notes that authenticated users can update raw_user_meta_data.
6. Inspect privileged functions and server routes
Review Edge Functions and server routes that use a secret key or perform administrative operations. Each function must authenticate and authorize the actual caller before using privileged access. Supabase cautions that the platform’s verify_jwt check alone does not authenticate a caller who sends only an API key.
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7. Include Realtime and replication in the review
Page testing covers only the requests made by that page. Review which tables are published for Realtime or replication, and confirm sensitive tables have RLS and policies appropriate to subscriptions as well as ordinary queries. Supabase’s Production Checklist specifically calls out RLS and policies for sensitive replicated tables. Supabase Docs, API keys, accessed October 7, 2026, states that public Realtime connections have a maximum duration of 24 hours unless upgraded to user-level authentication.
8. Review project and authentication settings
Open Supabase’s Security Advisor and inspect its findings. Also check project-account MFA, email confirmation, and OTP expiry. Supabase’s Production Checklist recommends MFA and email confirmation, and recommends setting OTP expiry to 3600 seconds (one hour) or lower.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to do a ten-minute first-pass check
Use a test record and test accounts you control. Do not probe real users’ sensitive data. The expected result for an unauthorized read or change is denial or no rows, depending on the app’s design.
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- Minutes 0–2: Open Supabase Security Advisor and note exposed tables or other findings. Inspect the frontend bundle or repository for secret-key and service-role patterns. Do not share a live credential with a scanner or chat.
- Minutes 2–5: In Supabase’s table and policy views, list the exposed tables and confirm RLS is enabled. For each relevant table, inspect grants and policies separately for
SELECT,INSERT,UPDATE, andDELETE. - Minutes 5–7: Test as a signed-out visitor and as a second ordinary user. With a test record owned by the first account, try the reads or changes that should be forbidden to the second account. Verify the result is denial or no rows, as appropriate.
- Minutes 7–9: Review Storage policies and test private-file listing and fetching with a second account. Check Realtime and replication settings for sensitive tables.
- Minute 10: Review privileged functions for caller authentication and authorization, then check project MFA and authentication settings. Escalate complicated or uncertain findings for a fuller review.
When is a quick self-check enough?
A dashboard pass can reveal visible misconfiguration; it cannot establish that every access path behaves as intended. A deeper technical review should exercise the policy logic across roles, operations, row ownership, functions, and relevant Storage and Realtime paths.
| Review level | Scope | Evidence | What it establishes |
|---|---|---|---|
| Quick self-check | Visible settings and obvious exposure risks | Dashboard inspection and a few controlled manual tests | Triage only; it can surface issues but does not certify security |
| Deeper technical review | Tables, all relevant operations, roles, ownership cases, functions, Storage, and Realtime | Repeatable allow/deny tests, including database policy tests | Stronger validation of the intended rules; it is not automatically a penetration test or compliance assessment |
A ten-minute pass can answer “How do I check RLS on my Supabase tables?” at a basic level and may expose an obvious problem. It cannot answer “Is my Supabase database secure?” conclusively: that requires testing the full set of access rules and paths, not just finding RLS switched on.
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