POSIX subsystem crashes when you try to create a Telnet session in Windows

Applies to: Windows Server 2012 DatacenterWindows Server 2012 DatacenterWindows Server 2012 Standard


Assume that a computer is running a Telnet service of Subsystem for UNIX-based Applications in Windows 8, Windows Server 2012, Windows 7, or Windows Server 2008 R2. You establish a Telnet session on a client, and then close the Telnet session without closing the other processes that were spawned in the same Telnet session. When you try to create a new Telnet session, the Psxss.exe process crashes.


This issue occurs because a property of the Psxss.exe process is not updated when the Telnet session is closed. Therefore, when a new session is created, the property is invalid, and it causes the crash.


To resolve this issue, we have released a hotfix for Windows 8, Windows Server 2012, Windows 7, or Windows Server 2008 R2.
Before you apply the hotfix, check out the "Prerequisites" section in this article.

Hotfix information

Important Do not install a language pack after you install this hotfix. If you do, the language-specific changes in the hotfix will not be applied, and you will have to reinstall the hotfix. For more information, see Add language packs to Windows.

A supported hotfix is available from Microsoft. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing this specific problem.

If the hotfix is available for download, there is a "Hotfix Download Available" section at the top of this Knowledge Base article. If this section does not appear, submit a request to Microsoft Customer Service and Support to obtain the hotfix.

Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, visit the following Microsoft website: Note The "Hotfix Download Available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.

Hotfix detail information


To apply this hotfix, you must install Service Pack 1 for Windows 7 or Windows Server 2008 R2. And there is no prerequisite for Windows 8 and Windows Server 2012.

Registry information

To use the hotfix in this package, you do not have to make any changes to the registry.

Restart requirement

You may have to restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace a previously released hotfix.


Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.


See the terminology that Microsoft uses to describe software updates.