The May 2015 Cumulative Update for SharePoint 2013 contains numerous hotfixes and improvements for SharePoint Foundation 2013 and SharePoint Server 2013. The cumulative update package is multilingual and contains updates for all languages.

Before you start
This update fixes the issue with the SharePoint 2013 Service Pack 1 build version and can be installed with both SP 2013 SP 1 releases.
Since June 2014 the Cumulative Updates for SharePoint products releases on a monthly basis.
Since May 2015 the server proofing tools are included in the cumulative updates.
This cumulative update includes all patches since the Service Pack 1 release, but not the Service Pack 1 itself. You must install the Service Pack 1 before installing this cumulative update. Read how-to install Service Pack 1.
Because of the file size the cumulative update package has been divided in three parts; ubersrv.exe, ubersrv_1.cab and ubersrv_2.cab. You have to put them all in the same folder.

Installation instructions

  • Create a SharePoint Farm Backup.
  • Download all SharePoint Foundation and SharePoint Server packages.
  • Extract the previously downloaded files with a double-click.
  • Click «Continue»
  • Define the path in which you would like to extract the installation binaries and click OK. Use the same destination path for the other files.
  • Run the extracted EXE file as administrator.
  • Accept the license terms and click «Continue».
  • Repeat the previous two steps for the other EXE files in this folder.
  • Apply the updates to each SharePoint server in the farm.
  • As soon as the installation of the cumulative update has finished on all servers, run the SharePoint Configuration Wizard successively on each SharePoint server in the farm.
  • Restart the User Profile Service on affected servers.

Hotfix KB3039747 for SharePoint Foundation 2013: May 12, 2015
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Description of the SharePoint Foundation 2013 update package

Hotfix KB2965266 for SharePoint Server 2013: May 12, 2015
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Description of the SharePoint Server 2013 update package

Hotfix KB2965263 for Project Server 2013: May 12, 2015
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Description of the SharePoint Server 2013 with Project Server 2013 update package

Hotfix KB2965306 for Office Web Apps Server 2013: May 12, 2015
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Description of the Office Web Apps Server 2013 update package
This is a security fix, please refer to SharePoint updates are no longer available through Windows Update

SharePoint 2013 update portal
http://technet.microsoft.com/en-us/sharepoint/ee748587.aspx