Legacy devices are older systems that may no longer receive modern security updates, firmware fixes, or required migration steps. In cyber security, they are risky because their trust settings, certificates, and boot protections can become stale even while the hardware still works.
In Secure Boot environments, a legacy device may keep starting normally but stop receiving DB or DBX updates that approve good boot components and revoke known-bad ones. That creates a quiet gap: defenders can no longer refresh the device’s boot-time trust chain, so outdated code may remain allowed longer than intended. Attackers value these systems because frozen defenses are easier to study and bypass, while defenders must track which endpoints can still be updated, migrated, or isolated.