CVE-2021-40449VulnerabilityPublished 11/17/2021Updated 10/24/2026
CVE-2021-40449: Microsoft Windows Win32k Privilege Escalation Vulnerability
Affects Microsoft WindowsSource CISA KEV
Severity
HighNo CVSS score published yet
- Exploitation
Actively exploited – in CISA KEV since 11/17/2021
- KEV deadline
- 12/01/2021
- Ransomware
- Used in ransomware campaigns
- EPSS
- 81.9% chance of exploitation in 30 days – higher than 99% of CVEs
What to do
CISA required action
Apply updates per vendor instructions.
Description
CVE-2021-40449 is a high-severity privilege escalation vulnerability in Microsoft Windows Win32k component. It allows an authenticated user to escalate privileges. The vulnerability has been exploited in the wild and is known to have been used in ransomware campaigns. No specific affected versions or patch information is provided.