Known issues

The original update KB 4293807 for this security vulnerability was released on August 14, 2018. It exposed certain testing trace flags that were not intended for public release. These trace flags are usually off by default. Therefore, the update has been replaced. If you have previously applied the original update KB 4293807, we recommend that you install KB 4458621 as soon as possible.

You can optionally first uninstall update KB 4293807, but this is not necessary because update KB 4458621 supersedes and replaces KB 4293807.

More Information

How to obtain help and support for this security update

Help for installing updates: Windows Update: FAQ

Security solutions for IT professionals: TechNet Security Support and Troubleshooting

Help for protecting your Windows-based computer from viruses and malware: Microsoft Secure

Local support according to your country: International Support

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