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Release Date:



Security-only update

Improvements and fixes

This security update resolves security vulnerabilities in Scripting Engine, Hyper-V, Win32K, Adobe Type Manager Font Driver, Microsoft Outlook, Graphics component, Lightweight Directory Access Protocol and Windows OLE.

For more information about the security vulnerabilities resolved, please refer to the Security Update Guide.

Known issues in this update

Microsoft is not currently aware of any issues with this update.

How to get this update

To get the stand-alone package for this update, go to the Microsoft Update Catalog website.

Note The April update (KB4015548) mrxsmb.sys file version number is lesser than March update mrxsmb.sys (KB4012214). This is not an issue as the binary content of mrxsmb.sys is same in both these updates.


Mrxsmb.sys Version

March update KB4012214


April update KB4015548


More Information

  • The security fixes that are listed in this Security-only Quality Update (KB4015548) are also included in the April 2017 Security Monthly Quality Rollup, KB4015551. Installing either update KB4015548 or KB4015551 installs the security fixes that are listed here.

  • This Security-only Quality Update does not include security fixes for Internet Explorer. In order to obtain the security fixes for Internet Explorer, the Cumulative Security Update for Internet Explorer KB4014661 should also be installed. Note that the Security Monthly Quality Rollup does contain security updates for Internet Explorer.

  • If you use update management processes other than Windows Update, and you automatically approve all security updates classifications for deployment, this April 2017 Security-only Quality Update (KB4015548), April 2017 Security Monthly Quality Rollup KB4015551, and the Cumulative Security Update for Internet Explorer KB4014661 are deployed. We recommend that you review your update deployment rules to make sure the desired updates are deployed.

  • This Security Only Quality Update is not applicable for installation on a computer on which the Security Monthly Quality Rollup or Preview of Monthly Quality Rollup from April 2017 (or a later month) is already installed. This is because those updates contain all of the security fixes that are included in this Security-only Quality Update.

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