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Question

Claude Code 'fixed' my permission error by turning RLS off. Is that as bad as it sounds?

Solved · 2357 views · asked by harriet_g · edited
claude-codesupabasesecurityauth

I got new row violates row-level security policy for table "bookings" when saving a booking. I asked Claude Code to fix it and it wrote a migration:

alter table public.bookings disable row level security;

Everything works now. But the Supabase dashboard shows a red "RLS disabled" badge on the table and the Security Advisor has an error. My app only lets logged-in users see their own bookings in the UI, so does it matter?

What I’ve tried

Asked Claude Code if it's safe, it said the UI already filters by user so it's fine. That answer made me more nervous, not less.

Comment
Your nervousness is correct. Don't ship this. jb_supa · edited
ok, so not as fine as Claude said. Reading the answers now. harriet_g · edited
Saving this thread. I'm fairly sure Cursor did the exact same thing on one of my tables. vibeandchill · edited
Also: this is why a local Supabase for development is worth it. At least the damage stays on your laptop. sanne_dev · edited

3 answers

Marked as helpful by the asker
amir_h · edited

Yes, it's as bad as it sounds. The UI filter protects nothing.

Your anon key is in the browser bundle by design. Anyone can open devtools, copy it, and run:

const { data } = await supabase.from('bookings').select('*')

With RLS disabled, that returns every booking from every user. Names, phone numbers, whatever is in there.

Fix it properly:

alter table public.bookings enable row level security;

create policy "own bookings: select" on public.bookings
  for select to authenticated using ((select auth.uid()) = user_id);

create policy "own bookings: insert" on public.bookings
  for insert to authenticated with check ((select auth.uid()) = user_id);

The original error almost always means the insert did not set user_id, or set it to something other than the logged-in user. Make sure the insert includes user_id: session.user.id, or give the column default auth.uid() so the client can't get it wrong.

Then add a rule to your CLAUDE.md: never disable RLS, never use the service role key in client code. It will keep trying otherwise.

Comment
The insert wasn't sending user_id at all. Added the default and the two policies, works and the badge is green. Thank you. harriet_g · edited
Also worth running the Security Advisor after every AI session that touches migrations. It catches exactly this. lena_ops · edited
jb_supa · edited

One addition: since the table was open for a day, check your API logs in the dashboard for select calls on bookings that did not come from your own app's pages. If it was only a dev project, never mind.

Comment
Checked, nothing unusual. Only my own requests. Phew. harriet_g · edited
max_ships_it · edited

Had the same thing a month ago. What stopped it for me: a line in CLAUDE.md ("RLS stays enabled on every table. On an RLS error, fix the policy or the insert, never the table") plus a pre-commit hook that greps migrations for disable row level security and refuses the commit.

Comment
The pre-commit hook idea is great, adding it. harriet_g · edited

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