Escaping Firecracker from Guest Userspace
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Ranked by a public rubric, not by votes: what a comment adds counts, not who wrote it. How comments are ranked · Comment rules
Summary
Coinspect Security disclosed a Firecracker microVM escape, CVE-2026-122192, reachable from root in guest userspace. In snapshot-restored VMs using the File memory backend plus a balloon device, a failed memory-discard remap left a stale KVM slot, giving the guest access to live VMM memory. Versions 0.23.0 through 1.16.1 are affected; 1.16.2 and 1.17.0 fix it. A second seccomp bypass via io_uring is under review; AWS reports Lambda is unaffected. Coinspect tested Firecracker itself, not downstream sandbox services.