On May 14, 2026, Broadcom dropped an emergency security advisory (VMSA-2026-0003) resolving a high-severity privilege escalation vulnerability in VMware Fusion, the widely utilized macOS virtualization software.
Tracked as CVE-2026-41702, the critical security flaw allows a local, low-privileged user or a rogue background process to instantly bypass Apple’s security perimeters and seize complete, root-level control over the entire host operating system. Because virtualization tools require deep kernel access to run guest operating systems, leaving this vulnerability unpatched creates a massive security blind spot on developer workstations and enterprise endpoints alike.
The Technical Breakdown: Weaponizing the TOCTOU Window
Discovered and responsibly reported by security researcher Mathieu Farrell (@coiffeur0x90), the vulnerability lives inside a highly privileged SETUID binary packaged within the VMware Fusion core engine.
The exploit leverages a classic Time-of-Check to Time-of-Use (TOCTOU) race condition flaw.
How the Exploit Operates:
- The Flaw: When a system utility runs with elevated root permissions, it must double-check whether the user calling it has authorization to interact with a specific file or folder resource.
- The Timing Gap: A TOCTOU bug occurs when there is a microsecond delay between the moment the software verifies the file is safe (the Check) and the moment it executes the action (the Use).
- The Hijack: An attacker running a basic, unprivileged script on the Mac can manipulate the underlying file system during that exact split-second window—swapping a safe file for a malicious payload.
Because the SETUID binary has already verified the initial state, it blindly processes the attacker’s swapped file with full administrative root privileges. No administrative passwords, user consent pop-ups, or remote exploit frameworks are needed to achieve total system compromise.
Who is At Risk?
The attack surface impacts local environments where VMware Fusion is actively deployed to run virtualized Windows, Linux, or secondary macOS environments.
- Vulnerable Version: VMware Fusion 25H2 on macOS.
- The Threat Profile: Standard development workstations, shared corporate corporate endpoints, or multi-user Mac environments where a low-privileged insider or a compromised standard app could use this flaw as a springboard to compromise the underlying system hardware.
Remediation: No Workarounds Exist
Broadcom’s product security response team has confirmed that there are absolutely no configuration tweaks, command-line workarounds, or script blocks that can stop this local exploit path.
The only remediation is to upgrade the software application immediately:
- All users currently operating on VMware Fusion 25H2 must immediately pull down and install version 26H1 or higher.
Security engineering teams are strongly advised to run endpoint configuration audits across their MDM (Mobile Device Management) fleets to locate instances of version 25H2 and push the 26H1 package update over-the-air to sever this root escalation path before it can be weaponized during internal red-team operations or malware campaigns.
