March 22, 2018—KB4056567 Improvements and fixes for Universal C Runtime in Windows

• Addresses an issue in the Universal C Runtime (CRT) in which a race condition occurs when you update the global locale. This condition corrupts the current locale reference count and triggers a double free condition.
• Addresses an issue in which the Universal CRT experiences decreased performance in the _gcvt and _gcvt_s functions.
• Addresses an issue in the Universal CRT for the standard error (STDERR) stream in which the output to a file or pipe is fully buffered.
• Addresses an issue in the Universal CRT by adding the "x" access mode flag to support the fopen() function.

Method 1: Windows Update

This update is provided as an Optional update on Windows Update. For more information about how to run Windows Update, see How to get an update through Windows Update.

Method 2: Microsoft Update Catalog

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

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

Learn about the terminology that Microsoft uses to describe software updates.