How to secure a v0 + Supabase app

How do I add Supabase to a v0 project?

1. Open Project menu > Settings > Integrations and pick Supabase, or ask for it in the chat.
2. Let the integration provision the Supabase account. v0 adds the environment variables to the project.
3. From then on, v0 can generate and execute SQL against the database, including statements that drop tables.

Which Supabase variables are safe in v0?

Only variables with the NEXT_PUBLIC_ prefix reach the browser. The Supabase URL and publishable key may carry it. The secret key must not. Search the client build for a secret key before each deploy.

# Look for a secret key before you deploy. This must print nothing.
grep -rnE "sb_secret_|service_role" .next/static/ 2>/dev/null

How do I check the tables v0 created?

Tables made with SQL do not get RLS on their own. Run the query below in the Supabase SQL editor after v0 changes the schema, then add policies to each table it returns.

-- Tables in public without RLS. This must return no rows.
select c.relname
from pg_class c
join pg_namespace n on n.oid = c.relnamespace
where n.nspname = 'public' and c.relkind = 'r' and not c.relrowsecurity;

alter table public.tasks enable row level security;

create policy "tasks: owner reads" on public.tasks
  for select to authenticated
  using ((select auth.uid()) = user_id);

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

create policy "tasks: owner updates" on public.tasks
  for update to authenticated
  using ((select auth.uid()) = user_id)
  with check ((select auth.uid()) = user_id);

How do I guard Server Actions that use the secret key?

The secret key maps to service_role, which skips every policy. A Server Action or Route Handler that holds it is your only check, so write the check first.

• Read the signed-in user from the session on the server, not from a form field or a URL parameter.
• Confirm that user may touch the rows in the request before you run the query.
• Prefer the user's own session with the publishable key, so RLS still applies. Use the secret key only for work no user may do.
• Keep the secret key in a server-only variable without the NEXT_PUBLIC_ prefix.

Should v0 use Supabase MCP tools?

Marketplace integrations can expose remote MCP tools to v0, and the default is Ask for Approval. Keep that default. Supabase's MCP guide names prompt injection as the main LLM-specific attack.

• Scope the connection to one project.
• Use read-only mode for anything that runs unattended.
• Connect to the production project only when a task needs it.