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Microsoft Security Advisory CVE-2025-49734: PowerShell Direct Elevation of Privilege Vulnerability

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Évaluation

Difficulté
1/5
Temps estimé
Moins d'une heure
Accessibilité débutants
5/100
Type d'issue
Documentation
Clarté
À clarifier
Activité
À l'abandon
Stack technique
powershell
Domaine
security

Piste de recherche

This is a published Microsoft security advisory for CVE-2025-49734, not a task. The affected-versions table (PowerShell 7.5 at or below 7.5.2 and 7.4 at or below 7.4.11, patched in 7.5.3 and 7.4.12) and the pwsh -v check in the FAQ are the only concrete content. Questions about PowerShell specifics belong in a support question on the PowerShell/PowerShell repository, as the Discussion section says. There is no code change to make here.

Rédigé par le modèle d'indexation à partir du texte de l'issue.

Description

PowerShell Security

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:

  1. 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 [email protected].

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

CVE-2025-49734

Revisions

V1.0 (September 10, 2025): Advisory published.

Version 1.0
Last Updated 2025-09-10

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