A boot loop occurs when a device repeatedly restarts without completing the operating system startup process. The device may crash during loading, restart automatically, and repeat the cycle, leaving it unusable or difficult to access.
In cyber security, a boot loop is an availability problem: it can result from faulty updates, damaged system files, or software that causes a critical component to crash repeatedly. An attack may trigger one by feeding malformed data to an operating-system parser or package handler. Defenses include keeping devices and system components updated, avoiding untrusted app packages, and using recovery tools or vendor support to restore affected devices.