Cloud dependency is the reliance on remote servers for core features, storage, control, or authentication. In practice, a device or app may still run locally, but key functions only work if it can reach a vendor service. That can include account login, software updates, voice commands, telemetry, or even basic start-up checks.
In cyber security, cloud dependency matters because it expands the trust boundary. If the remote service is hacked, disabled, or changed, users can lose access or inherit new risk without touching the device itself. Attackers may target cloud accounts, APIs, or update systems to take over many devices at once. Defenders sometimes reduce this risk with local-first designs, offline modes, strong authentication, and the ability to inspect or self-host critical services. The less a product depends on a remote cloud, the less exposure it has to service outages, account takeover, and vendor lock-in.