What Is PII Leakage?

PII leakage is the unintended transmission of personally identifiable information to a third-party tag or platform, typically through a misconfigured tracking event, an overly broad data layer push, or a tag feature, like Advanced Matching, capturing more than intended. It's a failure mode distinct from a tag simply not firing correctly.

PII leakage is worth separating from the broader Data Leakage because the legal exposure is specific and immediate: under GDPR and CCPA, transmitting personal data to a third party without proper consent is itself the violation. It commonly happens through channels nobody’s watching: a Meta Pixel‘s Advanced Matching picking up a form field, a Query Parameters value carrying an email address, or a data layer event that includes a name where it shouldn’t. Payload Inspection is the only reliable way to catch it.