Firecracker

A researcher reported a full VM escape — guest-to-host root — against Vercel Sandbox’s Firecracker microVMs on EC2, and Vercel paid its maximum $50,000 bounty and confirmed a KVM zero-day. KVM is the industry-standard Linux hypervisor under most of the cloud, so a guest-to-host escape is the multi-tenant isolation nightmare. What is actually confirmed, what isn’t, why microVMs exist, and what a security leader should do before the CVE drops.