Linux KVM guest-host escape rated critical, may represent a new way to attack penguin-powered networking

Paulos Yibelo, the researcher who in early October claimed to have found a guest-host escape flaw in Linux KVM, the hypervisor used by most hyperscale clouds, has named the flaw PwnEscape and warned it might represent a new way to attack Linux – on top of being a 9.3-rated critical nasty in its own right. Yibelo’s work is now CVE-2026-99999. It is a scary bug because it makes a guest-host escape possible with a few malformed IPv4 packets.