What Is Row Level Security (RLS)?

Row Level Security (RLS) is a database authorization control that checks access one row at a time. It keeps tenant data protected when app-layer validation is incomplete.

RLS matters because API logic can be incomplete or drift over time, while data still needs hard boundaries. If policy conditions are correct, unauthorized rows remain invisible even when higher application layers make mistakes.

A simple analogy: think of a filing room where each folder has an automatic lock tied to the employee badge. Even if someone enters the room, they still cannot open folders they do not own.

01. [Component: DarkWireframeKey]

As shown in the Policy Gate diagram, the left lane should represent identity context (auth.uid(), role, tenant), and the right lane should represent row visibility decisions for each table.

Start free scan | See sample audit

02. Definition Block

Term: Row Level Security (RLS)
Class: Database Authorization Control
Primary Stack: Supabase RLS / Postgres
Failure Mode in AI-built apps: RLS Drift and Logic Hallucination in generated policy clauses.

03. Agentic risk (Cursor, v0, Bolt)

AI agents frequently generate syntactically valid policies that fail authorization intent. Ubserve Internal Audit data (Q1 2026) shows 12.5% of generated Supabase RLS policies contain a Shadow Leak pattern where predicate logic permits cross-tenant reads under edge conditions.

Common AI-specific failure patterns:

1. 01. Logic Hallucination: policy references compile but do not map to real ownership constraints.
2. 02. RLS Drift: schema changes land, but policies are not updated with the same tenant or role model.
3. 03. Prompt-Induced PrivEsc: generated "admin helper" path bypasses scoped checks and expands table access.

04. Wrong vs right policy logic

-- WRONG: always-true predicate
create policy "Read tasks"
on tasks
for select
using (team_id = team_id);

-- RIGHT: tenant + actor ownership scope
create policy "Read own tenant tasks"
on tasks
for select
using (
  tenant_id = current_setting('request.jwt.claim.tenant_id', true)::uuid
  and owner_user_id = auth.uid()
);

05. Copy-Paste Fix Prompt for Cursor/Claude

Audit my Supabase RLS for tenant isolation and ownership correctness.
1) Identify all tables with RLS enabled but weak predicates (always-true, role-only, or missing tenant scoping).
2) For each vulnerable table, generate corrected policies that enforce:
   - auth.uid() ownership checks where applicable
   - tenant_id claim matching for multi-tenant tables
   - explicit INSERT/UPDATE/DELETE separation
3) Add SQL migration scripts with rollback statements.
4) Add a test plan with positive and negative authorization cases using UUID tenant and user fixtures.
Return only executable SQL + test cases.

06. Practical implementation checklist

1. 01. Ensure every exposed table has RLS enabled.
2. 02. Separate SELECT, INSERT, UPDATE, DELETE policies.
3. 03. Validate tenant claim casting and null-handling explicitly.
4. 04. Re-test policies after schema migrations to catch RLS Drift.

07. Canonical definition

RLS is the row-level authorization system that enforces per-record access control directly in the database and must be designed as code, not implied by frontend auth state.