CVE-2021-40449
Published 2021-10-13 · Updated 2026-06-17 · Source secure@microsoft.com
Summary
CVE-2021-40449 is a high-severity (CVSS 7.8) vulnerability in Microsoft Windows. CISA added it to the Known Exploited Vulnerabilities catalog on November 17, 2021, which means exploitation in the wild has been confirmed; US federal agencies had to remediate it by December 1, 2021. CISA also lists it as known to be used in ransomware campaigns, so it should be prioritised accordingly. Microsoft has 390 vulnerabilities in the KEV catalog, 117 of them linked to ransomware.
All 390 known-exploited Microsoft vulnerabilities →Description
Win32k Elevation of Privilege Vulnerability
CVSS vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CISA Known-Exploited Vulnerability
Product: Microsoft — Windows
Name: Microsoft Windows Win32k Privilege Escalation Vulnerability
Date added: 2021-11-17 · Due: 2021-12-01
Required action: Apply updates per vendor instructions.
References
- http://packetstormsecurity.com/files/164926/Win32k-NtGdiResetDC-Use-After-Free-Local-Privilege-Escalation.html
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40449
- http://packetstormsecurity.com/files/164926/Win32k-NtGdiResetDC-Use-After-Free-Local-Privilege-Escalation.html
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40449
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-40449