VirtualBox receives experimental KVM support

Oracle has integrated experimental support for KVM (Kernel-based Virtual Machine) into the current developer builds of VirtualBox. As can be seen from the VirtualBox issue tracker on GitHub, the new function enables the use of the native Linux hypervisor as a backend. The integration is done via the Native Execution Manager (NEM), which already supports Hyper-V (Windows) and the Apple Hypervisor (macOS).

The implementation is currently only available in manually created development builds. Users must apply patches to the VirtualBox source code and compile the system with the configure flags --with-kvm --disable-kmods. The KVM backend thereby eliminates the dependency on VirtualBox's own kernel modules, which can increasingly cause problems under Linux kernels from version 6.12 onwards.

Advantages in Kernel Conflicts

KVM support proves particularly useful when the proprietary VirtualBox modules cause difficulties. This applies, for example, to systems with active kernel signature checking or environments where conflicts occur between the VirtualBox and KVM modules. A kernel patch released by Oracle in October 2025 also enables the coexistence of both systems by re-exporting the functions kvm_enable_virtualization() and kvm_disable_virtualization().

Parallel to Oracle's development, the independent open-source project virtualbox-kvm from Cyberus Technology already exists. It has been offering a KVM backend for VirtualBox since 2024, supporting features like nested virtualization. The last release appeared in early February 2026 (support for VirtualBox 7.1.6a).

Security Aspects and Outlook

From a security perspective, the KVM backend reduces the attack surface, as it is integrated directly into the kernel as a Type 1-like hypervisor. This reduces potential vulnerabilities compared to Type 2 hypervisors with their own kernel modules. Known vulnerabilities in VirtualBox often affect GPU and 3D components; similar problems also exist with QEMU/KVM in the virtio-gpu implementation.

Whether and when Oracle will integrate KVM support into a stable VirtualBox version is currently open; after all, the function is explicitly in an early experimental stage. For users who want to rely entirely on KVM, QEMU/KVM remains the mature alternative with native KVM integration and high performance.

With this step, Oracle is following its competitor VMware: Broadcom began preparing the use of KVM in its virtualization software at the end of 2024. However, there have been no updates or an official timeline for this overhaul since then.

(fo)