On September 3, 2026, Broadcom published security advisory VMSA-2026-0007, addressing two vulnerabilities in VMware Workstation and Fusion that allow a local administrator inside a guest virtual machine to break out of the sandbox and execute arbitrary code on the underlying host operating system.

The update delivers version 26H1u1 for both desktop hypervisors. Broadcom explicitly noted that no workarounds exist for either vulnerability, leaving binary patching as the only effective mitigation path.

Confirmed

  • Advisory ID & release: Broadcom published VMSA-2026-0007 on 3 September 2026, releasing VMware Workstation Pro 26H1u1 and VMware Fusion Pro 26H1u1.
  • CVE-2026-59346 (CVSSv3 9.3 — Critical): An integer-overflow flaw in the VMXNET3 virtual network adapter. An attacker with local administrative privileges inside a guest VM can exploit this to execute code on the host system. Reported independently by researcher h4urek of secsys lab, alongside Y² and Stan S via Trend Micro’s Zero Day Initiative (ZDI).
  • CVE-2026-59347 (CVSSv3 8.1 — Important): A stack-based buffer overflow in the Host-Guest File System (HGFS) used for shared folders. An attacker with local admin privileges on a VM can execute code as the virtual machine's vmx process running on the host. Reported by Yeonghyeon Choi and Tianchu Chen of Tencent’s Xuanwu Lab.
  • Affected platforms: VMware Workstation versions 25H2 and 26H1 running on any host operating system (Windows and Linux); VMware Fusion versions 25H2 and 26H1 running on macOS.
  • Zero workarounds: Broadcom confirmed no configuration changes, feature toggles, or policy settings can prevent exploitation without upgrading to 26H1u1.

Unknown

  • In-the-wild exploitation: Neither Broadcom nor the reporting researchers have cited active zero-day exploitation or public proof-of-concept exploit chains prior to disclosure.
  • Type-1 hypervisor status: VMware ESXi is not listed in VMSA-2026-0007; the advisory scopes the current blast radius specifically to desktop hypervisor products.
  • Time-to-exploit window: Because the components involved (HGFS shared folders and VMXNET3 virtual adapters) are standard in virtual machine templates, reverse-engineering the 26H1u1 binary diff could yield weaponized guest-to-host breakout exploits rapidly.

Why it matters

Desktop hypervisors are standard infrastructure for malware triage, security research, and developer sandbox workflows. When analysts execute untrusted code or detonate suspect binaries, the containment model relies on guest isolation. A VM escape that requires only guest administrative privileges collapses that barrier: malware possessing or acquiring elevated rights inside the VM can compromise the analyst’s host workstation and any internal network interfaces connected to it.

Our take

Hypervisor escapes with CVSS scores above 9.0 are high-consequence findings because virtualization is treated as a security boundary, not merely an operating convenience. The fact that this requires guest admin rights narrows the threat from casual web drive-bys, but directly threatens malware analysis pipelines where samples routinely operate as root or SYSTEM. Because Broadcom confirmed no workarounds are available, teams utilizing Workstation or Fusion for untrusted analysis or sandbox automation must treat 26H1u1 as an immediate priority patch.

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