High CPU usage and performance issues occur when access-based enumeration is enabled in Windows 8.1 or Windows 7

Symptoms
Consider the following scenario:
  • You have a computer that is running Windows 8.1, Windows RT 8.1, Windows Server 2012 R2, Windows 7 Service Pack 1 (SP1), or Windows Server 2008 R2 SP1.
  • You have access-based enumeration enabled on a shared folder. Or you enable access-based enumeration on a DFS namespace on a folder.
  • You use the Server Message Block 2.0 file-sharing protocol. By default, this protocol is used on Windows-based computers.
  • You try to browse the contents of the shared folder. Or you try to do any other standard work that involves shared files.

In this scenario, CPU usage of the server seems to spike close to 100 percent, and you may experience performance issues such as delays.
Resolution

Hotfix information

A supported hotfix is available from Microsoft Support. 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, go to 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.

Prerequisites

To apply this hotfix, install update 2919355 in Windows 8.1 or Windows Server 2012 R2. Or, install Service Pack 1 in Windows 7 or Windows Server 2008 R2.

Restart requirement

You must restart the computer after you apply this hotfix.

Hotfix replacement information

This hotfix does not replace any previously released hotfix.
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
References
Learn about the terminology that Microsoft uses to describe software updates.
File Information
The English (United States) version of this software update installs files that have the attributes that are listed in the following tables. The dates and times for these files are listed in Coordinated Universal Time (UTC). Be aware that dates and times for these files on your local computer are displayed in your local time and with your current daylight saving time bias. The dates and times may also change when you perform certain operations on the files.

Windows 7 and Windows Server 2008 R2

Notes
  • The files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:
    Version Product Milestone Service branch
    6.1.760 1.22 xxxWindows 7 or Windows Server 2008 R2 SP1 LDR
  • GDR service branches contain only those fixes that are widely released to address widespread, critical issues. LDR service branches contain hotfixes in addition to widely released fixes.
  • The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed in the "Additional file information" section. MUM, MANIFEST, and the associated security catalog (.cat) files, are very important to maintain the state of the updated components. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.
x86 Windows 7
File nameFile versionFile sizeDateTimePlatform
Srv2.sys6.1.7601.22547313,85620-Dec-201301:00x86
x64 Windows 7 and Windows Server 2008 R2
File nameFile versionFile sizeDateTimePlatform
Srv2.sys6.1.7601.22547406,01620-Dec-201301:16x64
ia64 Windows Server 2008 R2
File nameFile versionFile sizeDateTimePlatform
Srv2.sys6.1.7601.22547799,23220-Dec-201300:41IA-64

Windows 8.1, Windows RT 8.1 and Windows Server 2012 R2

Notes
  • The files that apply to a specific product, milestone (RTM, SPn), and service branch (LDR, GDR) can be identified by examining the file version numbers as shown in the following table:
    VersionProductMilestoneService branch
    6.3.960 0.18 xxxWindows RT 8.1, Windows 8.1, and Windows Server 2012 R2RTMGDR
  • GDR service branches contain only those fixes that are widely released to address widespread, critical issues. LDR service branches contain hotfixes in addition to widely released fixes.
  • The MANIFEST files (.manifest) and the MUM files (.mum) that are installed for each environment are listed in the "Additional file information" section. MUM, MANIFEST, and the associated security catalog (.cat) files, are very important to maintain the state of the updated components. The security catalog files, for which the attributes are not listed, are signed with a Microsoft digital signature.
Windows RT 8.1
File nameFile versionFile sizeDateTimePlatform
Srv2.sys6.3.9600.18111521,72828-Oct-201516:24Not applicable
x86 Windows 8.1
File nameFile versionFile sizeDateTimePlatform
Srv2.sys6.3.9600.18111562,68828-Oct-201516:43x86
x64 Windows 8.1 and Windows Server 2012 R2
File nameFile versionFile sizeDateTimePlatform
Srv2.sys6.3.9600.18111677,37628-Oct-201517:35x64

Additional file information

x86 Windows 7
File propertyValue
File nameUpdate.mum
File versionNot applicable
File size1,643
Date (UTC)20-Dec-2013
Time (UTC)06:51
PlatformNot applicable
File nameX86_36ebf8214e5828facbd0a32f76310226_31bf3856ad364e35_6.1.7601.22547_none_fd997073fc0a950c.manifest
File versionNot applicable
File size700
Date (UTC)20-Dec-2013
Time (UTC)06:51
PlatformNot applicable
File nameX86_microsoft-windows-smbserver-v2_31bf3856ad364e35_6.1.7601.22547_none_dc6018916df128ed.manifest
File versionNot applicable
File size2,655
Date (UTC)20-Dec-2013
Time (UTC)02:37
PlatformNot applicable
x64 Windows 7 and Windows Server 2008 R2
File propertyValue
File nameAmd64_63da24375a34d4d449457e3be5eb8da8_31bf3856ad364e35_6.1.7601.22547_none_82c1fdbb0205ba24.manifest
File versionNot applicable
File size704
Date (UTC)20-Dec-2013
Time (UTC)06:51
PlatformNot applicable
File nameAmd64_microsoft-windows-smbserver-v2_31bf3856ad364e35_6.1.7601.22547_none_387eb415264e9a23.manifest
File versionNot applicable
File size2,657
Date (UTC)20-Dec-2013
Time (UTC)03:05
PlatformNot applicable
File nameUpdate.mum
File versionNot applicable
File size1,853
Date (UTC)20-Dec-2013
Time (UTC)06:51
PlatformNot applicable
ia64 Windows Server 2008 R2
File propertyValue
File nameIa64_b3b9e3293113963cec166f9ce7e43ccf_31bf3856ad364e35_6.1.7601.22547_none_6dde45114a195541.manifest
File versionNot applicable
File size702
Date (UTC)20-Dec-2013
Time (UTC)06:50
PlatformNot applicable
File nameIa64_microsoft-windows-smbserver-v2_31bf3856ad364e35_6.1.7601.22547_none_dc61bc876def31e9.manifest
File versionNot applicable
File size2,656
Date (UTC)20-Dec-2013
Time (UTC)02:24
PlatformNot applicable
File nameUpdate.mum
File versionNot applicable
File size1,447
Date (UTC)20-Dec-2013
Time (UTC)06:50
PlatformNot applicable
Windows RT 8.1
File propertyValue
File nameArm_a88b019c9d0b4e7397f7d2dac6086573_31bf3856ad364e35_6.3.9600.18111_none_c309bfe792bb9a85.manifest
File versionNot applicable
File size700
Date (UTC)29-Oct-2015
Time (UTC)20:45
PlatformNot applicable
File nameArm_microsoft-windows-smbserver-v2_31bf3856ad364e35_6.3.9600.18111_none_6ed74d8811dc9122.manifest
File versionNot applicable
File size259,944
Date (UTC)28-Oct-2015
Time (UTC)17:07
PlatformNot applicable
File nameUpdate.mum
File versionNot applicable
File size1,594
Date (UTC)29-Oct-2015
Time (UTC)20:45
PlatformNot applicable
x86 Windows 8.1
File propertyValue
File nameUpdate.mum
File versionNot applicable
File size1,594
Date (UTC)29-Oct-2015
Time (UTC)20:45
PlatformNot applicable
File nameX86_570b6e0e61bcd21a11508db9b66f5870_31bf3856ad364e35_6.3.9600.18111_none_e84f129369c487c3.manifest
File versionNot applicable
File size700
Date (UTC)29-Oct-2015
Time (UTC)20:45
PlatformNot applicable
File nameX86_microsoft-windows-smbserver-v2_31bf3856ad364e35_6.3.9600.18111_none_6ed4db3011df725c.manifest
File versionNot applicable
File size259,944
Date (UTC)28-Oct-2015
Time (UTC)17:55
PlatformNot applicable
x64 Windows 8.1 and Windows Server 2012 R2
File propertyValue
File nameAmd64_060d1586cd1fa3f95e159143d53cfee2_31bf3856ad364e35_6.3.9600.18111_none_5131c01efb3f6004.manifest
File versionNot applicable
File size704
Date (UTC)29-Oct-2015
Time (UTC)20:45
PlatformNot applicable
File nameAmd64_microsoft-windows-smbserver-v2_31bf3856ad364e35_6.3.9600.18111_none_caf376b3ca3ce392.manifest
File versionNot applicable
File size259,948
Date (UTC)28-Oct-2015
Time (UTC)18:49
PlatformNot applicable
File nameUpdate.mum
File versionNot applicable
File size1,602
Date (UTC)29-Oct-2015
Time (UTC)20:45
PlatformNot applicable
Properties

Article ID: 2920591 - Last Review: 12/10/2015 08:58:00 - Revision: 3.0

Windows Server 2012 R2 Datacenter, Windows Server 2012 R2 Standard, Windows Server 2012 R2 Essentials, Windows Server 2012 R2 Foundation, Windows 8.1 Enterprise, Windows 8.1 Pro, Windows 8.1, Windows RT 8.1, Windows Server 2008 R2 Service Pack 1, Windows 7 Service Pack 1

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