A national ID number is a government-issued identifier used to uniquely recognize a person for public services, tax, education, voting, or other official records. Because it is stable and widely accepted, it is a high-value personal data element: if exposed together with a name, date of birth, address, or document scans, it can help attackers impersonate a victim or build convincing fraud profiles.
In cyber security, leaked national ID numbers matter because they can support identity theft, account recovery abuse, social engineering, and the creation of synthetic identities. Attackers may harvest them from data breaches, extortion listings, or poorly protected portals that store large records in bulk. Defenders reduce risk by limiting collection, restricting access, encrypting databases and archives, redacting identifiers in shared documents, and monitoring for unusual exports or mass document downloads.