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+---
+title: Apply Principle of Least Privilege
+impact: MEDIUM
+impactDescription: Reduced attack surface, better audit trail
+tags: privileges, security, roles, permissions
+---
+
+## Apply Principle of Least Privilege
+
+Grant only the minimum permissions required. Never use superuser for application queries.
+
+**Incorrect (overly broad permissions):**
+
+```sql
+-- Application uses superuser connection
+-- Or grants ALL to application role
+grant all privileges on all tables in schema public to app_user;
+grant all privileges on all sequences in schema public to app_user;
+
+-- Any SQL injection becomes catastrophic
+-- drop table users; cascades to everything
+```
+
+**Correct (minimal, specific grants):**
+
+```sql
+-- Create role with no default privileges
+create role app_readonly nologin;
+
+-- Grant only SELECT on specific tables
+grant usage on schema public to app_readonly;
+grant select on public.products, public.categories to app_readonly;
+
+-- Create role for writes with limited scope
+create role app_writer nologin;
+grant usage on schema public to app_writer;
+grant select, insert, update on public.orders to app_writer;
+grant usage on sequence orders_id_seq to app_writer;
+-- No DELETE permission
+
+-- Login role inherits from these
+create role app_user login password 'xxx';
+grant app_writer to app_user;
+```
+
+Revoke public defaults:
+
+```sql
+-- Revoke default public access
+revoke all on schema public from public;
+revoke all on all tables in schema public from public;
+```
+
+Reference: [Roles and Privileges](https://supabase.com/blog/postgres-roles-and-privileges)