NoSQL refers to database systems designed for flexible data models rather than fixed relational tables. Common NoSQL styles include document, key-value, wide-column, and graph databases. They are popular because they scale well across large datasets and can store heterogeneous data without forcing every record into the same schema.
In cyber security, NoSQL matters because its flexibility can also widen the attack surface. Applications may build dynamic queries, expose powerful admin APIs, or rely on loose authorization checks, creating opportunities for injection, privilege escalation, or data exposure when controls are weak. Defenders should enforce least privilege, validate input, review query construction, and secure access to replicas, backups, and management interfaces. In real attacks, NoSQL systems are often targeted through misconfiguration or application-layer abuse rather than the database engine alone.