ACTIVELY EXPLOITED

CVE-2019-0859: Microsoft Win32k Privilege Escalation Vulnerability

Facts
VendorMicrosoft
ProductWin32k
Actively exploitedYes
Added to CISA KEV3 Nov 2021
CISA federal deadline3 May 2022
Ransomware useKnown

Required action (CISA's text)

Apply updates per vendor instructions.

Description (NVD)

Microsoft Win32k fails to properly handle objects in memory causing privilege escalation. Successful exploitation allows an attacker to run code in kernel mode.

SOURCES

Other Microsoft flaws

Data from NVD, CISA KEV, FIRST EPSS and vendor advisories. Updated 10 Nov 2026.