An application sandbox is an isolation boundary that restricts what a software app can do on a device. It limits access to files, memory, sensors, other apps, and system resources unless those permissions are explicitly granted. On Android, the sandbox is a core defense that keeps one app from freely reading or modifying another app’s data.
In cyber security, sandboxes matter because they reduce the blast radius of compromise. If an attacker abuses a flaw inside one app, the sandbox can prevent direct access to the rest of the device. But it does not protect an app from leaking its own data. A disclosure bug, for example, may expose messages or tokens already loaded in the app’s process memory even though the wider platform remains intact. Defenders use sandboxing alongside permissions, patching, and app isolation to contain risk.