Microsoft Security Advisory CVE-2025-49734: PowerShell Direct Elevation of Privilege Vulnerability #78
Description
Microsoft Security Advisory CVE-2025-49734: PowerShell Direct Elevation of Privilege Vulnerability
Executive Summary
Improper restriction of communication channel to intended endpoints in Hyper-V allows an authorized attacker to elevate privileges locally.
System administrators are advised to update Windows and PowerShell 7 to an unaffected version (see affected software).
Discussion
Please open a support question to discuss the PowerShell aspects of this advisory.
Affected Software
To be secure, the Virtual Machine guest must have the Windows patch, and any instance of PowerShell 7 must be patched.
Windows
To find the patches, see CVE-2025-49734.
PowerShell 7
The vulnerability affects PowerShell 7 prior to the following versions:
| PowerShell 7 Version | Affected version | Patched Version |
|---|---|---|
| 7.5 | <= 7.5.2 | 7.5.3 |
| 7.4 | <= 7.4.11 | 7.4.12 |
The vulnerability affects PowerShell when running on the following operating systems:
| Operating System | Affected |
|---|---|
| Windows | Yes |
| macOS | No |
| Linux | No |
Advisory FAQ
How do I know if I am affected?
If all of the following are true:
- Run
pwsh -v, then, check the version in the table in Affected Software to see if your version of PowerShell 7 is affected.
How do I update to an unaffected version?
Follow the instructions at Installing PowerShell 7 to install the latest version of PowerShell 7.
Updating PowerShell 7 using Microsoft Update
Updating PowerShell 7 using Microsoft Update
What privileges could be gained by an attacker who successfully exploited the vulnerability?
The attacker, initially a non-admin user on the host, could hijack the PowerShell Direct session intended for communication between the admin user on host and a guest VM. This unauthorized access enables the attacker to impersonate the admin host user in communications with the guest, potentially manipulating or controlling guest-side operations.
Why am I getting login failure events on my unpatched guest VM?
To ensure compatibility with unpatched guests, the new client attempts a login. This will produce an event in the Security Event log with event id 4625. The username will be ?‹PSDirectVMLegacy> and the domain will be 䕖卒佉N.
This event should stop when you patch your guest.
Note: The ?‹PSDirectVMLegacy> and 䕖卒佉N text is verbatim - this is what the user sees.
Where can I find information about additional mitigation steps?
Please see additional mitigations required for the Windows portion of this issue in CVE-2025-49734.
Other Information
Reporting Security Issues
If you have found a potential security issue in PowerShell 7,
please email details to secure@microsoft.com.
Support
You can ask questions about this issue on GitHub in the PowerShell organization.
This is located at https://github.com/PowerShell/.
The Announcements repo (https://github.com/PowerShell/Announcements)
will contain this bulletin as an issue and will include a link to a discussion issue where you can ask questions.
Disclaimer
The information provided in this advisory is provided "as is" without warranty of any kind. Microsoft disclaims all warranties, either express or implied, including the warranties of merchantability and fitness for a particular purpose. In no event shall Microsoft Corporation or its suppliers be liable for any damages whatsoever including direct, indirect, incidental, consequential, loss of business profits or special damages, even if Microsoft Corporation or its suppliers have been advised of the possibility of such damages. Some states do not allow the exclusion or limitation of liability for consequential or incidental damages so the foregoing limitation may not apply.
What if the update breaks my script or module?
You can uninstall the newer version of PowerShell 7 and install the previous version of PowerShell 7.
This should be treated as a temporary measure.
Therefore, the script or module should be updated to work with the patched version of PowerShell 7.
Acknowledgments
QWangWang
Microsoft recognizes the efforts of those in the security community who help us protect customers through coordinated vulnerability disclosure.
See acknowledgments for more information.
External Links
Revisions
V1.0 (September 10, 2025): Advisory published.
Version 1.0
Last Updated 2025-09-10