Need to Know restricts access to information based on job requirements, even if someone has appropriate security clearance. Having a Top Secret clearance does not grant access to all Top Secret information—you must also demonstrate a legitimate need for specific data to perform your duties.
This principle applies beyond classified government systems. In business contexts, employees in the HR department might have access to personnel records generally, but only those working on a specific investigation need access to the relevant individual’s file.
CISSP Relevance
Need to Know connects Domain 2 (Asset Security) with data classification and Domain 5 (Identity and Access Management) for access decisions. The exam tests understanding of how need to know complements security clearances and how organizations implement this principle through access controls and data handling procedures.
Government guidance appears in Information Security Oversight Office.
Related terms: Data Classification, Least Privilege