Why Running EPT Won't Protect You From Januscape

Januscape (CVE-2026-53359) is a Linux KVM/x86 use-after-free that corrupts the host's shadow page-table bookkeeping. The reliable outcome is a host crash; public research describes a full guest-to-host escape that runs code on the host as root. The flawed assumption dates back to 2010, affects both Intel and AMD KVM hosts, and takes two coupled patches to close completely. We reproduced the memory corruption and the host denial-of-service primitive in our lab. In this live stream, we break down how the bug works, why applying only the earlier companion fix leaves the host exposed, and how to check and protect affected hypervisors without rebooting.