The vulnerability was reported to Microsoft by Vasily Berdnikov and Boris Larin from Kaspersky Lab.
Vulnerable component: Windows
CVSSv3 score: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H/E:H/RL:O/RC:C
CWE-ID: CWE-119 - Memory corruption
The vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to a boundary error when processing objects in memory within the Win32k component. A local user can create a malicious application, launch it on the system and execute arbitrary code with SYSTEM privileges.
Note: this vulnerability is being actively exploited in the wild.