An authoritative source is the trusted system of record for a specific data field. When multiple applications share data, this source is the one used to decide what is correct for values such as identity details, permissions, account status, or service eligibility. Other systems may cache or replicate the data, but they should treat the authoritative source as the reference point.
In cyber security, defining authoritative sources helps reduce inconsistency, fraud, and unauthorized changes. Strong governance makes it harder for attackers to alter records in one place while leaving other systems unaware. Defenders use this concept in access control, logging, and integrity checks, especially during integrations and migrations. In real attacks, criminals often exploit weak trust boundaries by injecting false data into a non-authoritative system, hoping it will later be accepted downstream. Clear source-of-truth rules make such tampering easier to detect and contain.