Third-Party Breach

A third-party breach is a security incident in which an organization's data, systems, or operations are compromised through a vulnerability or failure at one of its external vendors or partners rather than through a direct attack. Third-party breaches are among the most damaging and costly cyber incidents because they exploit the trust relationships between organizations and their vendors, often bypassing the first party's own security controls entirely. Continuous monitoring and outside-in vendor assessment are the primary defenses against third-party breach exposure.