CVE-2026-41702: VMware Fusion Privilege Escalation Flaw

CVE-2026-41702 Overview

CVE-2026-41702 is a Time-of-Check Time-of-Use (TOCTOU) race condition vulnerability in VMware Fusion. The flaw occurs during an operation performed by a SETUID binary. A local attacker with non-administrative user privileges can exploit the race window to escalate privileges to root on the macOS host where Fusion is installed. Broadcom published advisory #37454 covering this issue, which is categorized under CWE-367. The vulnerability requires local access and high attack complexity due to the timing-sensitive nature of TOCTOU exploitation, but successful exploitation yields full root compromise of the host system.

Critical Impact
Local attackers can win a race condition against a SETUID binary in VMware Fusion to gain root privileges on the host operating system.

Affected Products

VMware Fusion (refer to Broadcom Security Advisory #37454 for affected versions)
macOS hosts running VMware Fusion with the vulnerable SETUID binary
Workstation environments where Fusion is installed for non-administrative users

Discovery Timeline

2026-05-15 - CVE-2026-41702 published to NVD
2026-05-18 - Last updated in NVD database

Technical Details for CVE-2026-41702

Vulnerability Analysis

The vulnerability is a classic TOCTOU race condition [CWE-367] inside a SETUID binary shipped with VMware Fusion. SETUID binaries execute with the file owner's elevated privileges, typically root, regardless of the invoking user. When such a binary checks a property of a resource — such as ownership, permissions, or a path — and then acts on that resource in a separate operation, an attacker can swap the resource between the check and the use.

Because the binary runs as root during the action phase, the attacker can redirect the privileged operation to a resource they control. The result is a local privilege escalation from a standard user account to root. Exploitation requires winning a narrow timing window, which accounts for the high attack complexity in the vulnerability's scoring.

Root Cause

The root cause is non-atomic access to a filesystem resource within a SETUID code path. The SETUID binary validates a resource state — for example, a file path, symlink target, or ownership attribute — and then operates on that resource using a second syscall. Between those two operations, a local attacker substitutes the resource with one pointing to a sensitive target. The privileged action then executes against the attacker-controlled target.

Attack Vector

Exploitation requires local access with low-privileged user credentials on the macOS host. The attacker launches the vulnerable SETUID binary and concurrently runs a race-winning process that swaps the target resource — typically through symlink replacement, directory renaming, or filesystem path manipulation — during the binary's execution. Successful races allow the attacker to coerce the root-owned process into writing, reading, or executing against attacker-controlled paths, yielding root code execution. No user interaction is required beyond the attacker's own actions.

No public proof-of-concept exploit code is currently available. See the Broadcom Security Advisory #37454 for technical specifics released by the vendor.

Detection Methods for CVE-2026-41702

Indicators of Compromise

Unexpected child processes spawned by VMware Fusion SETUID binaries running as root
Symlink creation or rapid file replacement operations in directories accessed by Fusion helper binaries
Unauthorized root-owned files appearing in user-writable directories shortly after Fusion binary execution
Audit log entries showing privilege transitions from standard users to root via Fusion processes

Detection Strategies

Monitor execution of Fusion SETUID helper binaries by non-administrative user accounts and correlate with subsequent root-level filesystem activity
Use macOS Endpoint Security framework telemetry to detect symlink races and rapid rename() or unlink() operations targeting paths used by Fusion
Alert on new root-owned binaries, LaunchDaemons, or sudoers entries created within seconds of Fusion process activity

Monitoring Recommendations

Enable detailed process and file integrity telemetry on all macOS endpoints running VMware Fusion
Track invocations of SETUID binaries within the Fusion installation directory and flag unusual frequency patterns
Review unified logs for posix_spawn or execve calls into Fusion helper paths originating from standard user sessions

How to Mitigate CVE-2026-41702

Immediate Actions Required

Apply the patched VMware Fusion release identified in Broadcom Security Advisory #37454 on every affected macOS host
Inventory all systems running VMware Fusion and prioritize multi-user workstations for immediate remediation
Restrict local interactive logins on Fusion-enabled hosts to trusted administrators until patching is complete

Patch Information

Broadcom has released a security update addressing this TOCTOU flaw. Administrators should consult Broadcom Security Advisory #37454 for the fixed version numbers and download instructions. Apply the vendor-supplied update through the standard VMware Fusion auto-update mechanism or by downloading the patched installer from Broadcom.

Workarounds

No official vendor workaround is documented; apply the patch as the primary remediation
Limit which local user accounts can execute VMware Fusion through macOS parental controls or application allowlisting until patches are deployed
Remove VMware Fusion from shared or kiosk systems where untrusted local users could attempt the race

bash

# Verify the installed VMware Fusion version on macOS
/Applications/VMware\ Fusion.app/Contents/Library/vmware-vmx --version

# List SETUID binaries within the Fusion bundle for audit purposes
find /Applications/VMware\ Fusion.app -perm -4000 -type f -ls