CVE-2021-40444
Published: November 3, 2021
Official Description
Microsoft MSHTML contains a unspecified vulnerability that allows for remote code execution.
CISA KEV Advisory
Microsoft MSHTML Remote Code Execution Vulnerability
Microsoft MSHTML contains a unspecified vulnerability that allows for remote code execution.
Apply updates per vendor instructions.
Risk Analysis
Microsoft MSHTML contains an unspecified vulnerability that allows for remote code execution. The high EPSS score of 0.94332 indicates a very high likelihood of exploitation, making this a critical vulnerability. This vulnerability is confirmed as exploited by CISA.
This vulnerability is actively exploited in the wild and is listed in CISA's Known Exploited Vulnerabilities catalog. The nature of remote code execution suggests it is remotely exploitable, likely through specially crafted files or web content.
Apply all available security updates from Microsoft for affected systems. Implement robust endpoint protection and user awareness training to prevent execution of malicious content.
Technical Analysis
CVE-2021-40444 requires local access, meaning attackers must already have a foothold on the target system.
Exploitation requires some privileges, which limits the exposure to scenarios where an attacker has already gained initial access.
CISA has added CVE-2021-40444 to the Known Exploited Vulnerabilities (KEV) catalog, confirming active exploitation in the wild. U.S. federal agencies are required to patch this within the mandated timeframe, and all organizations should treat remediation as urgent.
Affected Vendors & Products
Exploit & PoC Resources
All References (1)
Quick Facts
Recommended Actions
- →Apply vendor patches immediately
- →Monitor CVE-2021-40444 in threat intel feeds
- →Review IDS/IPS signatures for exploitation attempts
- !CISA KEV: Federal agencies must patch per BOD 22-01 timeline
- !Active exploitation confirmed — treat as P1