A confidentiality breach is an incident where sensitive information is accessed, copied, or removed without authorization. In cyber security, it is one of the core data-security failures because it exposes data that was meant to stay private, such as employee records, customer files, credentials, or regulated health information.
These breaches often happen when attackers use stolen credentials, exploit a vulnerable service, abuse a misconfiguration, or move through connected cloud and SaaS systems until they reach valuable data. The impact is not limited to theft: it can trigger privacy notifications, contract issues, regulatory review, and trust loss. Defenders reduce the risk with least-privilege access, strong authentication, encryption, logging, segmentation, and rapid incident response that preserves evidence, scopes exposure, and revokes compromised tokens or accounts.