NIST SP 800-53 Rev. 5 AC-10 — Concurrent Session Control

What this control requires

Limit concurrent sessions for each account or account type to an organization-defined number to prevent unauthorized access and manage resource usage. This control supports the Session Management System capability within the Access Control family.

In plain English

Limit concurrent sessions for each account or account type to an organization-defined number to prevent unauthorized access and manage resource usage. In practice, this means you can prove you account management-level controls on a defined cadence.

Why it matters

SP 800-53 is the catalogue every U.S. federal authorisation (FedRAMP, FISMA, CMMC) and most regulated industries point at. A missing control surfaces as a Plan of Action & Milestones (POA&M) item that an Authorizing Official must approve before the Authority To Operate is granted or renewed.

What an auditor looks for

A 3PAO (FedRAMP) or Independent Assessor (NIST RMF) tests against NIST SP 800-53A assessment procedures. For each control they expect a documented implementation that addresses every assessment objective (Examine, Interview, Test) and an implementation summary in the System Security Plan.

Within Access Control, the assessor will trace your implementation back to the catalogue reference (Control AC-10) and look for objective evidence on the latest two assessment cycles.

How to implement

1. Write a short policy stating intent, scope and named owner.
2. Encode it as a platform guardrail — SCP, Azure Policy initiative, Organisation Policy, or repository policy.
3. Wire a monitoring signal that catches drift (CSPM rule, SIEM rule, scheduled query, Workspace alert) and ticket it.
4. Review on a documented cadence and capture the review in the risk register or compliance tracker.

Operational checklist

• Account. Document the trigger, the owner and the cadence.
• Usage. Document the trigger, the owner and the cadence.
• Access. Document the trigger, the owner and the cadence.
• Review. Document the trigger, the owner and the cadence.
• Concurrent. Document the trigger, the owner and the cadence.
• Scope: management, access control, organization, system, session control, identity, review, capability.

Evidence to collect

• Identity Scan. IAM / IdP exports — Entra ID, Okta, IAM Identity Center, Workspace directory — showing accounts, roles, MFA state and last sign-in.

Identity analytics (Okta, SailPoint, Access Analyzer) demonstrates least-privilege. Focus: Concurrent Session Control.

How it maps to other frameworks

Computed from shared tags, control component and key-operation subjects — handy when you are reconciling controls across an audit.

• CIS Controls v8 6.7 — Centralize Access Control
• NIST SP 800-171 Rev. 3 3.1.7 — Least Privilege - Privileged Functions
• BSI C5:2020 PS-04 — Physical site access control
• ISO/IEC 27001:2022 A.8.2 — Privileged access rights
• ISO/IEC 27701:2025 A.3.8 — Identity management

Related controls in NIST SP 800-53 Rev. 5

• Control AC-5 — Separation Of Duties
• Control AC-6(6) — Privileged Access By Non-Organizational Users
• Control AC-3(12) — Assert And Enforce Application Access
• Control AC-11 — Device Lock
• Control AC-17(9) — Disconnect Or Disable Access
• Control AC-14 — Permitted Actions Without Identification Or Authentication

References

• NIST Computer Security Resource Center — NIST SP 800-53 Rev. 5
• Catalogue identifier: Control AC-10

Topics: identity accessidentity managementaccess reviewprivileged access