CVE-2026-12781: EaseUS Partition Master Privilege Escalation

CVE-2026-12781 Overview

CVE-2026-12781 is an improper access control vulnerability [CWE-266] in the epmntdrv.sys kernel driver shipped with EaseUS Partition Master up to version 14.5. The flaw resides in an unknown function within the kernel driver component, where insufficient access restrictions allow a low-privileged local user to interact with privileged driver functionality. Successful exploitation can compromise confidentiality, integrity, and availability on the affected host. The vendor has confirmed that the issue affects older versions only and has been remediated in the current release. Public exploit details are referenced in third-party vulnerability databases, raising the risk of opportunistic abuse on unpatched systems.

Critical Impact
A local, authenticated attacker can abuse the epmntdrv.sys kernel driver to bypass access controls and gain elevated privileges on Windows hosts running vulnerable EaseUS Partition Master builds.

Affected Products

EaseUS Partition Master versions up to and including 14.5
Component: Kernel Driver epmntdrv.sys
Platform: Microsoft Windows hosts with the vulnerable driver installed

Discovery Timeline

2026-06-21 - CVE-2026-12781 published to NVD
2026-06-22 - Last updated in NVD database

Technical Details for CVE-2026-12781

Vulnerability Analysis

The vulnerability is classified under [CWE-266] Incorrect Privilege Assignment. The epmntdrv.sys driver exposes functionality that should be restricted to privileged callers, but its access control implementation permits low-privileged users to invoke sensitive operations. Because Windows kernel drivers run in ring 0, any improperly gated I/O control path becomes a direct route to SYSTEM-level code execution or arbitrary memory access. The attacker requires local access and low privileges, with no user interaction needed. The impact spans confidentiality, integrity, and availability of the local system.

Root Cause

The root cause is improper access control on a driver entry point in epmntdrv.sys. The driver does not adequately validate the privilege level or origin of callers issuing IOCTL requests. As a result, operations intended for the EaseUS user-mode service can be reached directly by unprivileged processes through DeviceIoControl calls against the driver's device object.

Attack Vector

Exploitation requires local code execution on the target Windows host under any authenticated user context. The attacker opens a handle to the driver's exposed device object and issues IOCTL requests that perform privileged kernel actions. Public technical references describe this pattern as a local privilege escalation primitive, where the unprotected driver interface is leveraged to read, write, or manipulate kernel-controlled resources. The vulnerability is not exploitable remotely and does not require user interaction beyond the attacker's own session.

No verified proof-of-concept code is reproduced here. Refer to the VulDB entry for CVE-2026-12781 and the Winslow 1984 CVE Collection write-up for technical details on the exposed IOCTL interface.

Detection Methods for CVE-2026-12781

Indicators of Compromise

Presence of epmntdrv.sys from EaseUS Partition Master 14.5 or earlier in C:\Windows\System32\drivers\ or vendor install directories
Unexpected processes opening handles to the EaseUS driver device object (for example \\.\EPMNTDRV) outside the EaseUS service context
Non-EaseUS binaries issuing DeviceIoControl calls against the driver

Detection Strategies

Inventory endpoints for vulnerable epmntdrv.sys versions using EDR file-hash and version queries
Hunt for low-privileged processes obtaining handles to the EaseUS driver and immediately spawning SYSTEM-context children
Correlate driver load events (Windows Event ID 6) with unusual subsequent token elevation or process injection activity

Monitoring Recommendations

Enable kernel driver load auditing and forward events to a centralized SIEM for retention and correlation
Alert on installations of legacy EaseUS Partition Master builds across managed Windows endpoints
Track Sysmon Event ID 1 and 7 for process creation and image loads referencing epmntdrv.sys

How to Mitigate CVE-2026-12781

Immediate Actions Required

Upgrade EaseUS Partition Master to the latest vendor release, which the vendor confirms resolves the issue
Uninstall EaseUS Partition Master from endpoints where it is not operationally required
Restrict local logon and limit standard user accounts on systems where the legacy driver remains installed

Patch Information

The vendor states that the vulnerability exists only in older product versions and that the issue is resolved in the current EaseUS Partition Master release. Administrators should download the latest version from the official EaseUS Partition Manager page and verify that the bundled epmntdrv.sys driver is updated post-installation.

Workarounds

Remove or disable the epmntdrv.sys driver where the EaseUS application is not actively in use
Apply Windows Defender Application Control or AppLocker rules to block execution of vulnerable driver versions
Enforce Microsoft's vulnerable driver blocklist policy to prevent loading of known-bad signed drivers

bash

# Verify installed EaseUS Partition Master driver version on Windows (PowerShell)
Get-Item "C:\Windows\System32\drivers\epmntdrv.sys" |
    Select-Object FullName, @{Name="Version";Expression={$_.VersionInfo.FileVersion}}

# Enable Microsoft vulnerable driver blocklist (Windows 11 / Server 2022+)
# Settings > Privacy & security > Windows Security > Device security >
# Core isolation > Microsoft Vulnerable Driver Blocklist: ON