NOTAFTER is a sudoers date constraint that defines the latest time at which a rule is valid. In practice, it lets an administrator say, “this command may be run only until this deadline.” It is the counterpart to NOTBEFORE, which sets the earliest valid time. These time limits are part of sudo policy, so they affect authorization decisions before a command is allowed to run.
In cyber security, NOTAFTER matters because time-based access controls are only as reliable as the time parsing behind them. If a privileged program interprets timestamps using an attacker-influenced timezone or ambiguous local time, the effective cutoff may shift. That can widen a temporary maintenance window or extend a privilege grant beyond what was intended. Defenders reduce this risk by using explicit time formats, limiting environment influence, and testing sudoers rules that depend on deadlines. When used carefully, NOTAFTER helps enforce short-lived, least-privilege access.