Glossary
Complete Mediation
Complete mediation requires that every access to a protected resource passes through an authorization check, without exception — no cached assumption from an earlier request, no internal path that bypasses the usual gate because it's assumed to be trusted already. The principle is easy to state and surprisingly easy to violate in practice, usually through a shortcut added for performance or convenience.
A common violation looks harmless in isolation: a component checks access once and then reuses that decision for several subsequent operations without re-checking, on the assumption that nothing relevant could have changed in between. When that assumption breaks — a permission is revoked mid-sequence, for instance — the shortcut is exactly what lets the now-invalid access continue.