This security update is rated Critical for all supported releases of Microsoft Windows. For more information, see the Affected Software and Vulnerability Severity Ratings section.
The security update addresses the vulnerabilities by correcting how SMBv1 handles specially crafted requests.
The following software versions or editions are affected. Versions or editions that are not listed are either past their support life cycle or are not affected. To determine the support life cycle for your software version or edition, see Microsoft Support Lifecycle.
The severity ratings indicated for each affected software assume the potential maximum impact of the vulnerability. For information regarding the likelihood, within 30 days of this security bulletin’s release, of the exploitability of the vulnerability in relation to its severity rating and security impact, please see the Exploitability Index in the March bulletin summary.
Note Please see the Security Update Guide for a new approach to consuming the security update information. You can customize your views and create affected software spreadsheets, as well as download data via a restful API. For more information, please see the Security Updates Guide FAQ. As a reminder, the Security Updates Guide will be replacing security bulletins. Please see our blog post, Furthering our commitment to security updates, for more details.
Update informations are on technet.microsoft.com