Functional security requirements definewhat security capabilities a system must provideto protect information and enforce policy. They describe required security functions such as identification and authentication, authorization, role-based access control, privilege management, session handling, auditing/logging, segregation of duties, and account lifecycle processes. Because of this,user privilegesare a direct and core concern of functional security requirements: the system must support controlling who can access what, under which conditions, and with what level of permission.
In cybersecurity requirement documentation, “privileges” include permission assignment (roles, groups, entitlements), enforcement of least privilege, privileged access restrictions, elevation workflows, administrative boundaries, and the ability to review and revoke permissions. These are functional because they require specific system behaviors and features—for example, the ability to define roles, prevent unauthorized actions, log privileged activities, and enforce timeouts or re-authentication for sensitive operations.
The other options are typically classified differently.System reliabilityandperformance/stabilityare generally non-functional requirements (quality attributes) describing service levels, resilience, and operational characteristics rather than security functions.Identified vulnerabilitiesare findings from assessments that drive remediation work and risk treatment; they inform security improvements but are not themselves functional requirements. Therefore, the option best aligned with functional security requirements is user privileges.