A virtual machine is supposed to create a boundary.
You run an application inside the VM, experiment with software, or handle an untrusted workload—and the host remains protected behind the virtualization layer.
But what happens when an attacker finds a way across that boundary?
Broadcom has patched two vulnerabilities in VMware Workstation and Fusion that can allow an attacker with administrative privileges inside a virtual machine to execute code on the underlying host. The vulnerabilities are tracked as CVE-2026-59346 and CVE-2026-59347.
The first is the more serious one.
CVE-2026-59346 is an integer-overflow vulnerability in the VMXNET3 virtual network adapter and carries a CVSS score of 9.3. An attacker who already has local administrative privileges inside a VM using VMXNET3 could potentially use the flaw to execute code on the host.
The second, CVE-2026-59347, is a stack-based buffer overflow in HGFS, VMware’s Host-Guest File System. It has a CVSS score of 8.1 and could allow code execution with the privileges of the VMX process running on the host.
This is what makes these vulnerabilities interesting.
The attacker doesn’t start by attacking the host.
The attack can start inside the VM.
Compromise the VM → gain administrative access → exploit the virtualization layer → reach the host.
That is essentially a VM escape.
And once the host is compromised, the attacker may have a much larger opportunity than the original VM.
The affected versions are VMware Workstation 25H2 and 26H1, and VMware Fusion 25H2 and 26H1. Broadcom has released 26H1u1 to address both vulnerabilities, and there are no workarounds listed.
The bigger lesson is simple:
A virtual machine is only as isolated as the virtualization layer protecting it.
We often think about patching the operating system inside the VM.
But the components connecting the guest and the host—network adapters, file-sharing mechanisms, guest tools and virtual devices—are also part of the attack surface.
When one of those components fails, the attacker may no longer be interested in the VM.
The host becomes the target.
And that is why VM-escape vulnerabilities deserve attention beyond their CVSS score.
