chs.us — Carl Sampsonhttps://chs.us/en-uscarl.sampson@gmail.com (Carl Sampson)carl.sampson@gmail.com (Carl Sampson)Fri, 24 Jul 2026 00:00:00 +0000Multi-tenant isolation as defense-in-depth: when WHERE owner_user_id isn't enoughhttps://chs.us/2026/07/multi-tenant-isolation-defense-in-depth/Fri, 24 Jul 2026 00:00:00 +0000carl.sampson@gmail.com (Carl Sampson)https://chs.us/2026/07/multi-tenant-isolation-defense-in-depth/Every query that returns user data filters by owner. That's the contract — and one forgotten WHERE clause leaks another tenant's data. Here's a second, automatic layer that fails closed, built on a SQLAlchemy do_orm_execute hook.SecurityMulti-TenantSqlalchemyPostgresAppsecDefense-in-DepthOast