The WTSQuerySessionInformation function returns ambiguous IPv6 address data on a computer that is running Windows Vista, Windows 7, Windows Server 2008 or Windows Server 2008 R2

Consider the following scenario:

• On a computer that is running Windows Vista, Windows 7, Windows Server 2008, or Windows Server 2008 R2, an application calls the WTSQuerySessionInformation function to query the IP address of a terminal server client.
• The terminal server client has an IPv6 address that contains several contiguous blocks of zeros.

In this scenario, the WTSQuerySessionInformation function returns ambiguous data. Therefore, the application cannot rely on this function to retrieve the IPv6 address of the terminal server client.

For example, the following is the actual client IPv6 address:In compliance with the IPv6 specification, this address can be abbreviated by using double-colon characters (::). Therefore, the following is the abbreviated form of the address:However, the WTSQuerySessionInformation function returns a WTS_CLIENT_ADDRESS structure that resembles the following:In this example, the double-colon characters are returned as "00 00" instead of as the correct number of zeros. In this situation, the application cannot interpret which one of the following is the correct full IPv6 address:

• fe80:0000:385f:e84b:ac02:f69c:0000:0000
• fe80:0000:0000:385f:e84b:ac02:f69c:0000
• fe80:0000:0000:0000:385f:e84b:ac02:f69c

Hotfix information

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 the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.

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, contact 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 Web site: 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.

Prerequisites

To apply this hotfix, your computer must be running one of the following operating systems:

• Windows Vista Service Pack 1 (SP1)
• Windows Server 2008
• Windows 7
• Windows Server 2008 R2

Registry information

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

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any other hotfixes.

File information

The English (United States) version of this hotfix installs files that have the attributes that are listed in the following tables. The dates and the times for these files are listed in Coordinated Universal Time (UTC). The dates and the times for these files on your local computer are displayed in your local time together with your current daylight saving time (DST) bias. Additionally, the dates and the times may change when you perform certain operations on the files.

Windows Vista and Windows Server 2008 file information notes

Important Windows Vista hotfixes and Windows Server 2008 hotfixes are included in the same packages. However, only "Windows Vista" is listed on the Hotfix Request page. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows Vista" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.

• The files that apply to a specific product, SR_Level (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table.

  Version	Product	SR_Level	Service branch
  6.0.600 0 . 20xxx	Windows Vista	RTM	LDR
  6.0.600 1 . 22xxx	Windows Vista and Windows Server 2008	SP1	LDR
  6.0.600 2 . 22xxx	Windows Vista and Windows Server 2008	SP2	LDR

• Service Pack 1 is integrated into the release version of Windows Server 2008. Therefore, RTM milestone files apply only to Windows Vista. RTM milestone files have a 6.0.0000.xxxxx version number.

For all supported x86-based versions of Windows Server 2008 and of Windows Vista

For all supported x64-based versions of Windows Server 2008 and of Windows Vista

For all supported IA-64-based versions of Windows Server 2008

Windows 7 and Windows Server 2008 R2 file information notes

Important Windows 7 hotfixes and Windows Server 2008 R2 hotfixes are included in the same packages. However, hotfixes on the Hotfix Request page are listed under both operating systems. To request the hotfix package that applies to one or both operating systems, select the hotfix that is listed under "Windows 7/Windows Server 2008 R2" on the page. Always refer to the "Applies To" section in articles to determine the actual operating system that each hotfix applies to.

For all supported x86-based versions of Windows 7

For all supported x64-based versions of Windows 7 and of Windows Server 2008 R2

For all supported IA-64-based versions of Windows Server 2008 R2

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

Request for Comments (RFC) 4291

Because of how certain styles of IPv6 addresses are allocated, some addresses may contain long strings of zero bits. There is a special syntax to simplify the presentation of these zero bits. That is, double-colon characters (::) can be used to indicate one or more groups of 16 bits of zero. These double-colon characters can also be used to compress leading zeros or trailing zeros in an address.

Note The double-colon characters can appear only one time in a particular address.

For more information about software update terminology, click the following article number to view the article in the Microsoft Knowledge Base: