A database schema migration is a controlled structural change to a database, such as adding or renaming tables, changing columns, or converting stored records to a new format. Unlike a simple data import, a migration can rewrite existing data and change how the application reads and writes it.
In cyber security, migrations matter because they sit on a trust boundary: if they fail, the application can lose access to account data, permissions, audit logs, or configuration state. Attackers may exploit weak migration logic through crafted input, while defenders rely on careful migration design to prevent corruption and unsafe rollback. Good practice includes backups, staging tests, versioned migrations, and rollback plans, especially for upgrades that must transform live production data.