CVE-2025-41246: VMware Tools Auth Bypass Vulnerability

CVE-2025-41246 Overview

CVE-2025-41246 is an improper authorisation vulnerability in VMware Tools for Windows. The flaw stems from how VMware Tools handles user access controls on Windows guest virtual machines. A non-administrative user on a guest VM, who is already authenticated through vCenter or ESX, can exploit this issue to access other guest VMs in the environment. Successful exploitation requires the attacker to possess valid credentials for both the targeted VMs and for vCenter or ESX. The weakness is tracked as CWE-863: Incorrect Authorization and was published by Broadcom under Security Advisory #36149.

Critical Impact
Authenticated adversaries can cross the guest VM trust boundary and reach other guest VMs managed by the same vCenter or ESX host.

Affected Products

VMware Tools for Windows (see Broadcom Security Advisory #36149 for affected version ranges)
Environments managed by VMware vCenter Server
Environments managed by VMware ESX/ESXi hosts

Discovery Timeline

2025-09-29 - CVE-2025-41246 published to NVD
2026-06-17 - Last updated in NVD database

Technical Details for CVE-2025-41246

Vulnerability Analysis

CVE-2025-41246 is an authorisation flaw in VMware Tools for Windows. VMware Tools runs inside a Windows guest and mediates several interactions between the guest and the hypervisor management plane, including guest operations invoked through vCenter or ESX. The affected code path does not correctly verify that the authenticated principal is authorised to act against the specific guest VM being targeted. As a result, a user with low privileges inside one guest VM can pivot to operations against other guest VMs that share the same vCenter or ESX authentication scope.

The attack requires adjacent network access, high attack complexity, and high privileges to initiate. However, once conditions are met, the scope changes and the impact extends to the confidentiality, integrity, and availability of other guest VMs. This makes the issue relevant to multi-tenant environments where guest VMs are assumed to be isolated from one another at the management-plane level.

Root Cause

The root cause is improper authorisation logic [CWE-863] in VMware Tools for Windows. The component evaluates authentication state against vCenter or ESX but fails to enforce a per-target access check when a guest-side request references a different guest VM. Authorisation is effectively decoupled from the identity of the resource being acted on.

Attack Vector

An attacker first authenticates to vCenter or ESX with valid credentials and obtains non-administrative access to at least one Windows guest VM running the vulnerable VMware Tools build. From that foothold, the attacker issues guest operations that reference other guest VMs whose credentials they also know. Because VMware Tools does not properly evaluate authorisation for the referenced target, the operation succeeds against a VM the attacker should not be able to reach directly. No exploit code is publicly available at the time of publication and CVE-2025-41246 is not listed in the CISA Known Exploited Vulnerabilities catalog. Broadcom Security Advisory #36149 is the authoritative source for technical details.

Detection Methods for CVE-2025-41246

Indicators of Compromise

Guest operations against a VM initiated from a session on a different guest VM without an operational reason.
vCenter or ESX audit entries showing a single non-administrative user authenticating and issuing guest operations across multiple guest VMs in a short window.
Unexpected process launches, file transfers, or script execution inside a guest VM that correlate to VMware Tools guest-operation APIs.
Authentication events for guest credentials arriving through the VMware Tools channel rather than standard remote-access protocols such as RDP or WinRM.

Detection Strategies

Correlate vCenter or ESX guest-operation audit logs with endpoint telemetry inside each guest VM to identify operations that did not originate from a legitimate administrative workflow.
Baseline which user accounts normally invoke VMware Tools guest operations and alert on deviations, particularly from non-administrative accounts.
Hunt for lateral movement patterns where credentials for multiple guest VMs are used by the same session within minutes of each other.

Monitoring Recommendations

Forward vCenter, ESX, and Windows guest event logs into a central analytics platform and normalise them for cross-source correlation.
Monitor vmtoolsd.exe process activity and child processes on Windows guests for command execution that maps to guest-operation APIs.
Alert on non-administrative vCenter or ESX accounts that touch more than one guest VM within a short interval.

How to Mitigate CVE-2025-41246

Immediate Actions Required

Review Broadcom Security Advisory #36149 and apply the fixed VMware Tools for Windows build to all affected guest VMs.
Rotate credentials for guest VMs and for vCenter or ESX accounts that may have been exposed to low-privileged users.
Audit vCenter and ESX role assignments and remove standing guest-operation privileges from accounts that do not require them.
Restrict management-network reachability so that only administrative jump hosts can talk to vCenter and ESX APIs.

Patch Information

Broadcom has published fixed versions of VMware Tools for Windows in Security Advisory #36149. Administrators should consult the advisory for the exact fixed build numbers matching their deployed release train and update all Windows guest VMs. VMware Tools updates can be delivered through vCenter Update Manager, in-guest package managers, or the standard VMware Tools installer.

Workarounds

Until patching completes, limit non-administrative user access on Windows guest VMs and enforce least privilege on vCenter and ESX roles.
Segment guest VMs into separate vCenter permission scopes so that a single compromised account cannot address unrelated tenants.
Enforce strong, unique credentials on each guest VM and disable shared local administrator accounts across the estate.

bash

# Verify installed VMware Tools version on a Windows guest
"C:\Program Files\VMware\VMware Tools\VMwareToolboxCmd.exe" -v

# From PowerCLI, list VMware Tools versions across the estate
Connect-VIServer -Server vcenter.example.local
Get-VM | Select-Object Name, @{N='ToolsVersion';E={$_.Guest.ToolsVersion}}, @{N='ToolsStatus';E={$_.Guest.ToolsVersionStatus}}