This security update includes improvements and fixes that were a part of update KB4012218 (released March 21, 2017), and also resolves the following:
Security updates to Windows scripting engine, Hyper-V, libjpeg image-processing library, Adobe Type Manager Font Driver, Win32K, Microsoft Outlook, Internet Explorer, Graphics Component, Windows kernel-mode drivers, and Lightweight Directory Access Protocol.
For more information about the security vulnerabilities resolved, please refer to the Security Update Guide.