Rls Doctor MCP server

RLS Doctor

Don't trust your RLS. Prove it.

Can user A read user B's rows? Row Level Security is one of Postgres's strongest isolation tools, and one of the easiest to leave half-configured. You enable RLS, add a policy, and move on — but policies OR-combine, WITH CHECK silently falls back to USING, table owners bypass RLS entirely, and TRUNCATE is never protected at all.

rls-doctor reads your catalog and tells you what's actually reachable. And with probe, it stops analyzing and just shows you, impersonating your app roles in a transaction it always rolls back.

npx rls-doctor check    # reads DATABASE_URL or SUPABASE_DB_URL
npx rls-doctor demo     # no database needed: disposable Postgres, proven leak

RLS Doctor Report
Generated: 2026-07-12T00:00:00.000Z
Schemas: public

Summary: 1 tables, 0 policies, highest risk HIGH
Findings: critical 0, high 1, medium 0, low 0, info 0
RLS Score: 90/100

public.orders
  RLS disabled; force RLS disabled; 0 policies
  [HIGH] RLS-disabled table is reachable by an application role
    public.orders has no row-level checks; Application role authenticated and
    can exercise SELECT granted to authenticated.
    Fix: Enable RLS and add least-privilege policies for each application role.
    Suggested SQL:
      alter table "public"."orders" enable row level security;

Prove a cross-tenant leak instead of guessing

Most RLS review is reading policies and hoping. probe is behavioral:

rls-doctor probe --connection "$DATABASE_URL" --schema public \
  --app-roles authenticated --subjects \
  00000000-0000-0000-0000-000000000001 \
  00000000-0000-0000-0000-000000000002

It sets request.jwt.claims inside the transaction, so auth.uid() resolves to each real Supabase user, then counts whose rows that identity can read.

- [high] probe-cross-owner-read rls_doctor_demo.orders:
  Role authenticated reads rows across 2 distinct owner_id values
- [high] probe-cross-subject-read rls_doctor_demo.orders:
  Role authenticated reads rows belonging to other users

It never mutates anything. probe opens begin ... read only and always rolls back — safe against a production read replica.

Install

npx rls-doctor check              # no install
npm install -g rls-doctor         # global

Requires Node.js 20 or later. Prefer DATABASEURL or SUPABASEDB_URL with read-only audit credentials — passing a secret via --connection exposes it in shell history and process listings.

Commands

rls-doctor check --schema public --fail-on high
rls-doctor explain public.profiles
rls-doctor probe --app-roles authenticated --owner-columns tenant_id

check options

Shortened. The full README is on GitHub.