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CVE-2021-40444: Microsoft MSHTML Remote Code Execution Vulnerability
Microsoft MSHTML · in CISA KEV since 2021-11-03
2021-11-03added to KEV
2021-11-17federal remediation due date
97.45%EPSS exploit probability (30 days) 99.9th percentile
8.8 HIGHCVSS 3.1
Knownknown ransomware use
49days from NVD publication to KEV
What it is
Microsoft MSHTML contains a unspecified vulnerability that allows for remote code execution.
Required action (CISA)
Apply updates per vendor instructions.
| CWE | CWE-22 |
|---|---|
| CVSS vector | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:L |
| NVD published | 2021-09-15 (Analyzed) |
Original records: NVD · CISA KEV · JSON: /api/cve/CVE-2021-40444.json · all KEV CVEs
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Get the full file: Exploited Vulnerabilities Brief – September 2026 ($29): this month's KEV additions ranked by EPSS, ransomware use and due date, ready to hand to a patch team. Checkout by Polar.
Get the full file: Exploited Vulnerabilities Brief – September 2026 ($29): this month's KEV additions ranked by EPSS, ransomware use and due date, ready to hand to a patch team. Checkout by Polar.