Least Privilege
Security principle that every subject should have the minimum access needed to perform its function — and no more. Foundation of zero trust and defense-in-depth architectures.
Least privilege is a foundational security principle stating that every subject (user, service, agent) should have the minimum access necessary to perform its function — and no more. It is the cornerstone of zero trust and defense-in-depth architectures.
Why least privilege fails in practice
- Requesting access is slow, so people over-provision "to be safe"
- Nobody ever removes access, so grants only accumulate
- Coarse roles mean the only way to unblock someone is to over-grant
Making least privilege practical
- Default-deny + additive roles: start with zero, add small composable roles
- Just-in-time elevation: grant temporary access for rare operations
- Audit-driven right-sizing: revoke permissions that are never exercised
- Deny-wins guardrails: broad allow + explicit deny carve-outs
Related terms
An authorization evaluation rule where an explicit deny on any matching permission overrides all allow permissions. Used to enforce least-privilege without restructuring role hierarchies.
Authorization model where every request is verified independently — no implicit trust based on network location. "Never trust, always verify" applied to access control decisions.
Security control that prevents a single user from performing conflicting operations. For example, the same person cannot both create and approve a payment — requires two distinct identities.