Bare metal refers to software that runs directly on hardware without a general-purpose host operating system in between. In practice, that means the code talks to the CPU, memory, storage, and peripherals itself, often through firmware or custom drivers. This is common in embedded systems, hobby boards, bootloaders, and some specialized operating environments.
In cybersecurity, bare-metal setups matter because they reshape the trust boundary. They can reduce attack surface by removing a large OS layer, but they also shift more responsibility onto firmware, hardware assumptions, and low-level code quality. Defenders look closely at update paths, device initialization, and platform integrity, while attackers may target weak boot code, undocumented hardware behavior, or flawed ports. Bare metal is not automatically safer or riskier; it simply makes the underlying platform more visible and more critical.