CVE-2021-40449

Microsoft Windows 10 Version 1809, Microsoft Windows Server 2019, Microsoft Windows Server 2019 (Server Core installation)

Published 13 Oct 2021 · updated 17 Jun 2026 · Analyzed

7.8 High · CVSS 3.1, microsoft.com

Exploited in the wild

CISA added this to its Known Exploited Vulnerabilities catalog on 17 Nov 2021, with a remediation deadline of 1 Dec 2021 for US federal agencies. It has been used in ransomware campaigns.

Required action: Apply updates per vendor instructions.

Description

Win32k Elevation of Privilege Vulnerability

References

packetstormsecurity.com/files/164926/Win32k-NtGdiResetDC-Use-After-Free-Local-Privilege-Escalation.html · Exploit, Third Party Advisory, VDB Entry
portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40449 · Patch, Vendor Advisory
www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-40449 · US Government Resource