Firecracker is a lightweight virtual machine monitor (VMM) designed to launch very small virtual machines, often called microVMs. It provides hardware-backed isolation with a much smaller device model and faster startup than a full traditional hypervisor stack.
In cyber security, Firecracker matters because it helps cloud providers run untrusted or customer-controlled workloads with strong process and kernel separation. That reduces the blast radius of a compromise and makes sandboxing practical at scale. However, Firecracker only governs compute isolation; it does not automatically secure shared storage, snapshots, or other backend layers. If reused disk blocks are not zeroed, or if cached state is exposed, a workload may still recover residual data even when the VM boundary holds. Defenders use Firecracker to narrow attack surface, but they still need careful storage sanitation, secret handling, and tenant-aware cleanup.