TLDR Tech / InfoSec
Januscape: 16-Year-Old Linux KVM Bug Enables Cloud VM Escape Attacks
Januscape (CVE-2026-53359) is a use-after-free vulnerability in the shadow MMU of Linux's KVM hypervisor that has existed since 2010. The flaw allows a guest VM to corrupt host kernel memory on both Intel and AMD hosts. The bug stems from KVM matching shadow page table candidates by address alone, ignoring page type. A public PoC reliably panics the host within seconds to minutes, while a more severe path can turn the corrupted write into host code execution, threatening multi-tenant clouds like GCP and AWS that expose nested virtualization, including custom stacks that bypass QEMU entirely. Administrators should apply patches immediately or disable nested virtualization for untrusted guests if patching isn't possible.
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