(Pwn2Own) VMware ESXi VMXNET3 espQueueMask Out-Of-Bounds Write Local Privilege Escalation Vulnerability

July 29th, 2026
ZDI-26-495 ZDI-CAN-31293

CVE ID

CVE-2026-47876

CVSS Score

8.2 AV:L/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

Affected Vendors

VMware

Affected Products

ESXi

Vulnerability Details

This vulnerability allows local attackers to escalate privileges on affected installations of VMware ESXi. An attacker must first obtain the ability to execute high-privileged code on the target guest system in order to exploit this vulnerability.

The specific flaw exists within the implementation of the VMXNET3 virtual network adapter. The issue results from the lack of proper validation of user-supplied data, which can result in a write past the end of an allocated array. An attacker can leverage this vulnerability to escalate privileges and execute arbitrary code in the context of the hypervisor.

Additional Details

VMware has issued an update to correct this vulnerability. More details can be found at:
https://support.broadcom.com/web/ecx/support-content-notification/-/external/content/SecurityAdvisories/0/38017

Disclosure Timeline

  • 2026-06-02 - Vulnerability reported to vendor
  • 2026-07-29 - Coordinated public release of advisory
  • 2026-07-29 - Advisory Updated

Credit

Nguyen Hoang Thach (@hi_im_d4rkn3ss) of STARLabs SG (@starlabs_sg)

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