A remote code execution vulnerability exists in the way that the Microsoft Server Message Block 3.1.1 (SMBv3) protocol handles certain requests, aka 'Windows SMBv3 Client/Server Remote Code Execution Vulnerability'.
http://packetstormsecurity.com/files/156732/Microsoft-Windows-SMB-3.1.1-Remote-Code-Execution.html
http://packetstormsecurity.com/files/157110/SMBv3-Compression-Buffer-Overflow.html
http://packetstormsecurity.com/files/157901/Microsoft-Windows-SMBGhost-Remote-Code-Execution.html
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2020-0796