The vulnerability was privately reported to Microsoft by Kaspersky Lab.
Vulnerable component: Windows
CVSSv3 score: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C
CWE-ID: CWE-119 - Improper Restriction of Operations within the Bounds of a Memory Buffer
The vulnerability allows a local user to escalate privileges on the system.
The vulnerability exists due to a boundary error within Win32k.sys driver. A local user can create a specially crafted application, run it on vulnerable system and execute code withe superuser privileges.
Note: this vulnerability is being actively exploited in limited targeted attacks.