# NIST SP 800-53 Rev. 5 AC-4(19) — Validation Of Metadata - Source: https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-4-19-validation-of-metadata - Section: [Compliance](https://support.icompaas.com/compliance) › [NIST SP 800-53 Rev. 5 Controls](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5) › AC — Access Control - Last updated: 2026-06-05 - Publisher: iCompaas, Inc. (https://www.icompaas.com) **NIST SP 800-53 Rev. 5**·Control `AC-4(19)`·high·Component: **Access Control** ## What this control requires > When transferring information between different security domains, organizations must implement security or privacy policy filters on metadata. All information, including metadata and the associated data, should undergo filtering and inspection. This control supports the Governance capability within the Access Control family. > > — NIST SP 800-53 Rev. 5, Control AC-4(19) ### In plain English When transferring information between different security domains, organizations must implement security or privacy policy filters on metadata. In practice, this means you can prove you policy 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. This control is rated **high**. Auditors expect a named owner, a remediation SLA, and a tooling artefact that evidences continuous operation. ## 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-4(19)) and look for objective evidence on the latest two assessment cycles. ## How to implement #### Policy Management **Docs.** Keep each policy in version-controlled Markdown alongside the code that implements it; ship a signed PDF snapshot at each annual review and link the SHA into the SoA. ### Operational checklist - **Policy.** Document the trigger, the owner and the cadence. - **Access.** Document the trigger, the owner and the cadence. - **Information.** Document the trigger, the owner and the cadence. - **Metadata.** Document the trigger, the owner and the cadence. - **Security.** Document the trigger, the owner and the cadence. - **Scope:** management, access control, information, privacy, domains, privacy policy filters, metadata, inspection. ## Evidence to collect - **Policy Document.** A signed and version-controlled policy / standard / procedure document. Signed policy or standard documents the safeguard. Focus: Validation Of Metadata. ## Common pitfalls - Policies that no engineer has read; the version in Confluence drifts from the version that's actually being enforced. ## 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. - [**NIST SP 800-171 Rev. 3 3.1.9** — System Use Notification](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3/3-1-9-system-use-notification) - [**HIPAA (45 CFR Part 164) 164.310(a)(2)(iii)** — Facility Access Controls - Access Control and Validation Procedures](https://support.icompaas.com/compliance/hipaa/164-310-a-2-iii-facility-access-controls-access-control-and-validation-procedures) - [**SOC 2 (2017 TSC) P2.1** — Communication of Data Subject Choices and Consequences](https://support.icompaas.com/compliance/soc-2-trust-services-criteria/p2-1-communication-of-data-subject-choices-and-consequences) - [**ISO/IEC 27001:2022 A.5.1** — Policies for information security](https://support.icompaas.com/compliance/iso-27001-2022/a-5-1-policies-for-information-security) ## Related controls in NIST SP 800-53 Rev. 5 - [**Control AC-4(14)** — Security Or Privacy Policy Filter Constraints](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-4-14-security-or-privacy-policy-filter-constraints) - [**Control AC-4(15)** — Detection Of Unsanctioned Information](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-4-15-detection-of-unsanctioned-information) - [**Control AC-4(8)** — Security And Privacy Policy Filters](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-4-8-security-and-privacy-policy-filters) - [**Control AC-16(8)** — Association Techniques And Technologies](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-16-8-association-techniques-and-technologies) - [**Control AC-4(20)** — Approved Solutions](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-4-20-approved-solutions) - [**Control AC-4(13)** — Decomposition Into Policy-Relevant Subcomponents](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5/ac-4-13-decomposition-into-policy-relevant-subcomponents) ## References - [NIST Computer Security Resource Center — NIST SP 800-53 Rev. 5](https://csrc.nist.gov/Projects/risk-management/sp800-53-controls) - Catalogue identifier: `Control AC-4(19)` Topics: governance riskdata protectionpolicy managementprivacy management ## Related compliance guidance - [NIST SP 800-53 Rev. 5: a practical implementation guide for cloud teams](https://support.icompaas.com/compliance/nist-sp-800-53-rev-5): Start with the full NIST SP 800-53 implementation guide — scope, roadmap, evidence and how the assessment runs. - [NIST SP 800-171 and CMMC: a practical guide to protecting CUI in the cloud](https://support.icompaas.com/compliance/nist-sp-800-171-rev-3): If your obligation is protecting CUI in your own systems for a federal or defence contract, this derived subset — not the full catalogue — is the requirement. - [SOC 2 compliance: a practical implementation guide for cloud-native SaaS teams](https://support.icompaas.com/compliance/soc-2-trust-services-criteria): Most commercial SaaS already hold a SOC 2 Type 2, and FedRAMP 20x Class A is designed for providers that have one.