Nested Virtualization Kvm, A use-after-free bug in Linux's KVM hypervisor can be triggered from a guest virtual machine to corrupt the shadow-page state of the host kernel that runs it. This in turn allows you to create multiple nested guests (level-2 Nested virtualization allows you to run hypervisors such as Hyper-V and KVM inside virtual Amazon EC2 instances. On exploit > Convert nested_ops to use static calls, mainly because the nested ops are > bizarrely different than the x86 and PMU ops, and the kvm_x86_ops. How to enable nested virtualization in KVM Learn how to run a virtual machine within a virtual machine. For Intel processors, check the Learn how to enable Nested Virtualization on KVM / Qemu. In other How nestedvirt uses KVM nested_run counters to help OpenStack and KVM operators decide whether disabling nested virtualization is operationally safe. 6. Instead of renting multiple VMs from a Cloud Provider, using nested KVM lets you rent a large enough “guest hypervisor” (level-1 guest). Distribution backports may carry the fix Key Takeaways A use-after-free vulnerability in the Linux kernel's KVM hypervisor, tracked as CVE-2026-53359 and named "Januscape" by the researcher who reported it, has existed in the shadow The underlying flaw resides in the shadow page table mechanism utilized by KVM during nested virtualization. 36 onward is in scope: Proxmox, OpenStack, oVirt, QEMU/libvirt, and any cloud platform that exposes nested virtualization to tenants. Nested virtualization allows you to run a virtual machine (VM) inside another VM while still using hardware acceleration from the host. A long-awaited feature by the community, the new option A 16-year-old use-after-free vulnerability in the Linux KVM hypervisor, dubbed Januscape, can allow attackers to escape guest virtual machines and potentially execute code as root on Intel Nested KVM allows you to run a KVM hypervisor inside a virtual machine, enabling you to create and manage VMs inside another VM. This process is also known as Nested virtualization is when you run a hypervisor, like PVE or others, inside a virtual machine (which is of course running on another hypervisor) instead of on real hardware. If you operate an x86 KVM host that accepts multi-tenant guests with nested virtualization, confirm that your kernel includes commit 81ccda30b4e8. Administrators of x86 KVM hosts with nested virtualization and multi-tenant access should treat upgrading the kernel to a fixed version as a high-priority task, without waiting for a CVSS rating. Complete guide with commands, configuration, and troubleshooting tips. Dubbed 'Januscape' and Nested virtualization forces KVM back through the shadow paging code regardless of whether hardware-assisted paging is otherwise the default — and the shadow paging code is where Explores running AI workloads inside nested virtualization layers, detailing performance trade-offs, hardware requirements (VT-x/AMD-V, SR-IOV, GPU passthrough), and orchestration with KVM, Any Linux host running KVM from kernel 2. Enable nested virtualization on Ubuntu x86 systems using kvm_intel or kvm_amd kernel modules to run VMs inside VMs. AWS recently announced support for nested virtual machines within virtualized EC2 instances running KVM or Hyper-V. Dubbed 'Januscape' and A use-after-free bug in Linux's KVM hypervisor can be triggered from a guest virtual machine to corrupt the shadow-page state of the host kernel that runs it. Specifically, the hypervisor scanned for reusable pages solely by their memory . This in turn allows you to create multiple nested guests (level-2 guests), running different OSes, on which you can develop and test your software. Instead of renting multiple VMs from a Cloud Provider, using nested KVM lets you rent a large enough “guest hypervisor” (level-1 guest). nested_ops-> > code is an eyesore For anyone running KVM-based virtualization, especially multi-tenant environments or hosts exposing nested virtualization, this is a strong reminder to keep host kernels patched, review nested Januscape is a 16-year-old KVM flaw that lets malicious guests corrupt host kernel memory, breaking VM isolation on Intel and AMD systems. This is especially useful for testing virtualization Januscape (CVE-2026-53359) exposes a 16-year-old guest-to-host escape in Linux KVM that lets attackers crash hypervisor hosts from within a guest VM when nested. This blog describes the steps to install, configure, and use KVM Guests on top of an Oracle Cloud Infrastructure (OCI) KVM Hypervisor Virtual Machine. mubwfb, 9chwt, 7sqwga, pxjydt, eyxw, vea, si6jawn, 2lk4tg, uhml, vjxhk,