CVE-2021-40444VulnerabilityPublished 11/03/2021Updated 10/24/2026
CVE-2021-40444: Microsoft MSHTML Remote Code Execution Vulnerability
Affects Microsoft MSHTMLSource CISA KEV
Severity
HighNo CVSS score published yet
- Exploitation
Actively exploited – in CISA KEV since 11/03/2021
- KEV deadline
- 11/17/2021
- Ransomware
- Used in ransomware campaigns
- EPSS
- 97.8% chance of exploitation in 30 days – higher than 99% of CVEs
What to do
CISA required action
Apply updates per vendor instructions.
Description
CVE-2021-40444 is a high-severity remote code execution vulnerability in Microsoft MSHTML. It allows attackers to execute arbitrary code remotely. The vulnerability has been exploited in the wild and is known to be used in ransomware campaigns. No specific affected versions or patch information is provided in the available data.