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TI-2021-17496 Aliases CVE-2021-40444GHSA-2h32-fhf6-xhh5

Microsoft MSHTML Remote Code Execution Vulnerability

Priority CRITICAL 97Exploited in the wildCWE-22Published · Updated

Key facts

Attack vector
Network
Privileges required
None
User interaction
Required
Attack complexity
Low
Impact type
Code execution
Confidentiality · integrity · availability
Low · High · Low
Fix status
Fixed

Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Microsoft. Impact type from Microsoft.

Summary

Microsoft is investigating reports of a remote code execution vulnerability in MSHTML that affects Microsoft Windows. Microsoft is aware of targeted attacks that attempt to exploit this vulnerability by using specially-crafted Microsoft Office documents. An attacker could craft a malicious ActiveX control to be used by a Microsoft Office document that hosts the browser rendering engine. The attacker would then have to convince the user to open the malicious document. Users whose accounts are configured to have fewer user rights on the system could be less impacted than users who operate with administrative user rights. Microsoft Defender Antivirus and Microsoft Defender for Endpoint both provide detection and protections for the known vulnerability. Customers should keep antimalware products up to date. Customers who utilize automatic updates do not need to take additional action. Enterprise customers who manage updates should select the detection build 1.349.22.0 or newer and deploy it across their environments. Microsoft Defender for Endpoint alerts will be displayed as: “Suspicious Cpl File Execution”. Upon completion of this investigation, Microsoft will take the appropriate action to help protect our customers. This may include providing a security update through our monthly release process or providing an out-of-cycle security update, depending on customer needs. Please see the Mitigations and Workaround sections for important information about steps you can take to protect your system from this vulnerability. UPDATE September 14, 2021: Microsoft has released security updates to address this vulnerability. Please see the Security Updates table for the applicable update for your system. We recommend that you install these updates immediately. Please see the FAQ for important information about which updates are applicable to your system.

Why it matters now

Exploitation Active In CISA KEV since 2021-11-03CISA due date 2021-11-17Known ransomware use
EPSS 0.9784 99th percentileScored 2026-11-07
Public exploit Yes 2 exploit referencesTagged by NVD
Fix Fixed Microsoft: 13 updates

SSVC decision points

CISA ADP · SSVC 2.0.3

Exploitation
Active
Automatable
No
Technical impact
Total

The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.

Affected products

VendorProductAffected versionsFixed inStatusSource
MicrosoftWindows 10 Version 150710.0.10240.0 to before 10.0.10240.1906010.0.10240.19060Patch availableCNA
MicrosoftWindows 10 Version 160710.0.14393.0 to before 10.0.14393.465110.0.14393.4651Patch availableCNA
MicrosoftWindows 10 Version 180910.0.17763.0 to before 10.0.17763.218310.0.17763.2183Patch availableCNA
MicrosoftWindows 10 Version 180910.0.0 to before 10.0.17763.218310.0.17763.2183Patch availableCNA
MicrosoftWindows 10 Version 190910.0.0 to before 10.0.18363.180110.0.18363.1801Patch availableCNA
MicrosoftWindows 10 Version 200410.0.0 to before 10.0.19041.123710.0.19041.1237Patch availableCNA
MicrosoftWindows 10 Version 20H210.0.0 to before 10.0.19042.123710.0.19042.1237Patch availableCNA
MicrosoftWindows 10 Version 21H110.0.0 to before 10.0.19043.123710.0.19043.1237Patch availableCNA
MicrosoftWindows 76.1.0 to before 6.1.7601.257126.1.7601.25712Patch availableCNA
MicrosoftWindows 7 Service Pack 16.1.0 to before 6.1.7601.257126.1.7601.25712Patch availableCNA
MicrosoftWindows 8.16.3.0 to before 6.3.9600.201206.3.9600.20120Patch availableCNA
MicrosoftWindows Server 2008 R2 Service Pack 16.1.7601.0 to before 6.1.7601.257126.1.7601.25712Patch availableCNA
MicrosoftWindows Server 2008 R2 Service Pack 1 (Server Core installation)6.1.7601.0 to before 6.1.7601.257126.1.7601.25712Patch availableCNA
MicrosoftWindows Server 2008 Service Pack 26.0.6003.0 to before 6.0.6003.212186.0.6003.21218Patch availableCNA
MicrosoftWindows Server 2008 Service Pack 2 (Server Core installation)6.0.6003.0 to before 6.0.6003.212186.0.6003.21218Patch availableCNA
MicrosoftWindows Server 20126.2.9200.0 to before 6.2.9200.234626.2.9200.23462Patch availableCNA
MicrosoftWindows Server 2012 (Server Core installation)6.2.9200.0 to before 6.2.9200.234626.2.9200.23462Patch availableCNA
MicrosoftWindows Server 2012 R26.3.9600.0 to before 6.3.9600.201206.3.9600.20120Patch availableCNA
MicrosoftWindows Server 2012 R2 (Server Core installation)6.3.9600.0 to before 6.3.9600.201206.3.9600.20120Patch availableCNA
MicrosoftWindows Server 201610.0.14393.0 to before 10.0.14393.465110.0.14393.4651Patch availableCNA
MicrosoftWindows Server 2016 (Server Core installation)10.0.14393.0 to before 10.0.14393.465110.0.14393.4651Patch availableCNA
MicrosoftWindows Server 201910.0.17763.0 to before 10.0.17763.218310.0.17763.2183Patch availableCNA
MicrosoftWindows Server 2019 (Server Core installation)10.0.17763.0 to before 10.0.17763.218310.0.17763.2183Patch availableCNA
MicrosoftWindows Server 202210.0.20348.0 to before 10.0.20348.23010.0.20348.230Patch availableCNA
MicrosoftWindows Server version 200410.0.0 to before 10.0.19041.123710.0.19041.1237Patch availableCNA
MicrosoftWindows Server version 20H210.0.0 to before 10.0.19042.123710.0.19042.1237Patch availableCNA
  • Windows 10 Version 1507 VendorMicrosoft Affected 10.0.10240.0 to before 10.0.10240.19060 Fixed in 10.0.10240.19060 Patch available CNA
  • Windows 10 Version 1607 VendorMicrosoft Affected 10.0.14393.0 to before 10.0.14393.4651 Fixed in 10.0.14393.4651 Patch available CNA
  • Windows 10 Version 1809 VendorMicrosoft Affected 10.0.17763.0 to before 10.0.17763.2183 Fixed in 10.0.17763.2183 Patch available CNA
  • Windows 10 Version 1809 VendorMicrosoft Affected 10.0.0 to before 10.0.17763.2183 Fixed in 10.0.17763.2183 Patch available CNA
  • Windows 10 Version 1909 VendorMicrosoft Affected 10.0.0 to before 10.0.18363.1801 Fixed in 10.0.18363.1801 Patch available CNA
  • Windows 10 Version 2004 VendorMicrosoft Affected 10.0.0 to before 10.0.19041.1237 Fixed in 10.0.19041.1237 Patch available CNA
  • Windows 10 Version 20H2 VendorMicrosoft Affected 10.0.0 to before 10.0.19042.1237 Fixed in 10.0.19042.1237 Patch available CNA
  • Windows 10 Version 21H1 VendorMicrosoft Affected 10.0.0 to before 10.0.19043.1237 Fixed in 10.0.19043.1237 Patch available CNA
  • Windows 7 VendorMicrosoft Affected 6.1.0 to before 6.1.7601.25712 Fixed in 6.1.7601.25712 Patch available CNA
  • Windows 7 Service Pack 1 VendorMicrosoft Affected 6.1.0 to before 6.1.7601.25712 Fixed in 6.1.7601.25712 Patch available CNA
  • Windows 8.1 VendorMicrosoft Affected 6.3.0 to before 6.3.9600.20120 Fixed in 6.3.9600.20120 Patch available CNA
  • Windows Server 2008 R2 Service Pack 1 VendorMicrosoft Affected 6.1.7601.0 to before 6.1.7601.25712 Fixed in 6.1.7601.25712 Patch available CNA
  • Windows Server 2008 R2 Service Pack 1 (Server Core installation) VendorMicrosoft Affected 6.1.7601.0 to before 6.1.7601.25712 Fixed in 6.1.7601.25712 Patch available CNA
  • Windows Server 2008 Service Pack 2 VendorMicrosoft Affected 6.0.6003.0 to before 6.0.6003.21218 Fixed in 6.0.6003.21218 Patch available CNA
  • Windows Server 2008 Service Pack 2 (Server Core installation) VendorMicrosoft Affected 6.0.6003.0 to before 6.0.6003.21218 Fixed in 6.0.6003.21218 Patch available CNA
  • Windows Server 2012 VendorMicrosoft Affected 6.2.9200.0 to before 6.2.9200.23462 Fixed in 6.2.9200.23462 Patch available CNA
  • Windows Server 2012 (Server Core installation) VendorMicrosoft Affected 6.2.9200.0 to before 6.2.9200.23462 Fixed in 6.2.9200.23462 Patch available CNA
  • Windows Server 2012 R2 VendorMicrosoft Affected 6.3.9600.0 to before 6.3.9600.20120 Fixed in 6.3.9600.20120 Patch available CNA
  • Windows Server 2012 R2 (Server Core installation) VendorMicrosoft Affected 6.3.9600.0 to before 6.3.9600.20120 Fixed in 6.3.9600.20120 Patch available CNA
  • Windows Server 2016 VendorMicrosoft Affected 10.0.14393.0 to before 10.0.14393.4651 Fixed in 10.0.14393.4651 Patch available CNA
  • Windows Server 2016 (Server Core installation) VendorMicrosoft Affected 10.0.14393.0 to before 10.0.14393.4651 Fixed in 10.0.14393.4651 Patch available CNA
  • Windows Server 2019 VendorMicrosoft Affected 10.0.17763.0 to before 10.0.17763.2183 Fixed in 10.0.17763.2183 Patch available CNA
  • Windows Server 2019 (Server Core installation) VendorMicrosoft Affected 10.0.17763.0 to before 10.0.17763.2183 Fixed in 10.0.17763.2183 Patch available CNA
  • Windows Server 2022 VendorMicrosoft Affected 10.0.20348.0 to before 10.0.20348.230 Fixed in 10.0.20348.230 Patch available CNA
  • Windows Server version 2004 VendorMicrosoft Affected 10.0.0 to before 10.0.19041.1237 Fixed in 10.0.19041.1237 Patch available CNA
  • Windows Server version 20H2 VendorMicrosoft Affected 10.0.0 to before 10.0.19042.1237 Fixed in 10.0.19042.1237 Patch available CNA

CPE configurations NVD · 19

CPEVersionsRoleVendor
cpe:2.3:o:microsoft:windows_10_1507:*:*:*:*:*:*:*:*before 10.0.10240.19060VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:*:*before 10.0.14393.4651VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:*:*before 10.0.17763.2183VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10_1909:*:*:*:*:*:*:*:*before 10.0.18363.1801VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10_2004:*:*:*:*:*:*:*:*before 10.0.19041.1237VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10_20h2:*:*:*:*:*:*:*:*before 10.0.19042.1237VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_10_21h1:*:*:*:*:*:*:*:*before 10.0.19043.1237VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_7:-:sp1:*:*:*:*:*:*not specified by NVDVulnerableMicrosoft
cpe:2.3:o:microsoft:windows_8.1:-:*:*:*:*:*:*:*not specified by NVDVulnerableMicrosoft
cpe:2.3:o:microsoft:windows_rt_8.1:-:*:*:*:*:*:*:*not specified by NVDVulnerableMicrosoft
  • cpe:2.3:o:microsoft:windows_10_1507:*:*:*:*:*:*:*:* Versions before 10.0.10240.19060 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10_1607:*:*:*:*:*:*:*:* Versions before 10.0.14393.4651 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10_1809:*:*:*:*:*:*:*:* Versions before 10.0.17763.2183 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10_1909:*:*:*:*:*:*:*:* Versions before 10.0.18363.1801 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10_2004:*:*:*:*:*:*:*:* Versions before 10.0.19041.1237 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10_20h2:*:*:*:*:*:*:*:* Versions before 10.0.19042.1237 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_10_21h1:*:*:*:*:*:*:*:* Versions before 10.0.19043.1237 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_7:-:sp1:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_8.1:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_rt_8.1:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Microsoft
Show 9 more CPE
CPEVersionsRoleVendor
cpe:2.3:o:microsoft:windows_server_2004:*:*:*:*:*:*:*:*before 10.0.19041.1237VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2008:-:sp2:*:*:*:*:*:*not specified by NVDVulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:*:*:*:*:x64:*r2 sp1VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:*not specified by NVDVulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2012:-:r2:*:*:*:*:*:*not specified by NVDVulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:*before 10.0.14393.4651VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:*before 10.0.17763.2183VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:*before 10.0.20348.230VulnerableMicrosoft
cpe:2.3:o:microsoft:windows_server_20h2:*:*:*:*:*:*:*:*before 10.0.19042.1237VulnerableMicrosoft
  • cpe:2.3:o:microsoft:windows_server_2004:*:*:*:*:*:*:*:* Versions before 10.0.19041.1237 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2008:-:sp2:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2008:r2:sp1:*:*:*:*:x64:* Versions r2 sp1 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2012:-:*:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2012:-:r2:*:*:*:*:*:* Versions not specified by NVD Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2016:*:*:*:*:*:*:*:* Versions before 10.0.14393.4651 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2019:*:*:*:*:*:*:*:* Versions before 10.0.17763.2183 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_2022:*:*:*:*:*:*:*:* Versions before 10.0.20348.230 Vulnerable ·Microsoft
  • cpe:2.3:o:microsoft:windows_server_20h2:*:*:*:*:*:*:*:* Versions before 10.0.19042.1237 Vulnerable ·Microsoft

Remediation

Microsoft 13 updates

  • KB5019958
    IE Cumulative
    • Windows 7 for 32-bit Systems Service Pack 1 6.1.7601.26221
    • Windows 7 for x64-based Systems Service Pack 1 6.1.7601.26221
    • Windows 8.1 for 32-bit systems 6.3.9600.20670
    • Windows 8.1 for x64-based systems 6.3.9600.20670
    • Windows Server 2008 R2 for x64-based Systems Service Pack 1 6.1.7601.26221
    • Windows Server 2012 6.2.9200.23968
    • Windows Server 2012 R2 6.3.9600.20670
  • KB5005633
    Monthly Rollup
    • Windows 7 for 32-bit Systems Service Pack 1 6.1.7601.25712
    • Windows 7 for x64-based Systems Service Pack 1 6.1.7601.25712
    • Windows Server 2008 R2 for x64-based Systems Service Pack 1 6.1.7601.25712
    • Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) 6.1.7601.25712
  • KB5005627
    Security Only
    • Windows 8.1 for 32-bit systems 6.3.9600.20120
    • Windows 8.1 for x64-based systems 6.3.9600.20120
    • Windows Server 2012 R2 6.3.9600.20120
    • Windows Server 2012 R2 (Server Core installation) 6.3.9600.20120
Show 10 more Microsoft updates
  • KB5005623
    Monthly Rollup
    • Windows Server 2012 6.2.9200.23462
    • Windows Server 2012 (Server Core installation) 6.2.9200.23462
  • KB5005613
    Monthly Rollup
    • Windows 8.1 for 32-bit systems 6.3.9600.20120
    • Windows 8.1 for x64-based systems 6.3.9600.20120
    • Windows RT 8.1 6.3.9600.20120
    • Windows Server 2012 R2 6.3.9600.20120
    • Windows Server 2012 R2 (Server Core installation) 6.3.9600.20120
  • KB5005606
    Monthly Rollup
    • Windows Server 2008 for 32-bit Systems Service Pack 2 6.0.6003.21218
    • Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation) 6.0.6003.21218
    • Windows Server 2008 for x64-based Systems Service Pack 2 6.0.6003.21218
    • Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation) 6.0.6003.21218
  • KB5005575
    Security Update
    • Windows Server 2022 10.0.20348.230
    • Windows Server 2022 (Server Core installation) 10.0.20348.230
  • KB5005573
    Security Update
    • Windows 10 Version 1607 for 32-bit Systems 10.0.14393.4651
    • Windows 10 Version 1607 for x64-based Systems 10.0.14393.4651
    • Windows Server 2016 10.0.14393.4651
    • Windows Server 2016 (Server Core installation) 10.0.14393.4651
  • KB5005569
    Security Update
    • Windows 10 for 32-bit Systems 10.0.10240.19060
    • Windows 10 for x64-based Systems 10.0.10240.19060
  • KB5005568
    Security Update
    • Windows 10 Version 1809 for 32-bit Systems 10.0.17763.2183
    • Windows 10 Version 1809 for ARM64-based Systems 10.0.17763.2183
    • Windows 10 Version 1809 for x64-based Systems 10.0.17763.2183
    • Windows Server 2019 10.0.17763.2183
    • Windows Server 2019 (Server Core installation) 10.0.17763.2183
  • KB5005566
    Security Update
    • Windows 10 Version 1909 for 32-bit Systems 10.0.18363.1801
    • Windows 10 Version 1909 for ARM64-based Systems 10.0.18363.1801
    • Windows 10 Version 1909 for x64-based Systems 10.0.18363.1801
  • KB5005565
    Security Update
    • Windows 10 Version 2004 for 32-bit Systems 10.0.19041.1237
    • Windows 10 Version 2004 for ARM64-based Systems 10.0.19041.1237
    • Windows 10 Version 2004 for x64-based Systems 10.0.19041.1237
    • Windows 10 Version 20H2 for 32-bit Systems 10.0.19042.1237
    • Windows 10 Version 20H2 for ARM64-based Systems 10.0.19042.1237
    • Windows 10 Version 21H1 for 32-bit Systems 10.0.19043.1237
    • Windows 10 Version 21H1 for ARM64-based Systems 10.0.19043.1237
    • Windows 10 Version 21H1 for x64-based Systems 10.0.19043.1237
    • Windows Server, version 2004 (Server Core installation) 10.0.19041.1237
    • Windows Server, version 20H2 (Server Core Installation) 10.0.19042.1237
  • KB5005563
    IE Cumulative
    • Windows 7 for 32-bit Systems Service Pack 1 1.001
    • Windows 7 for x64-based Systems Service Pack 1 1.001
    • Windows 8.1 for 32-bit systems 1.001
    • Windows 8.1 for x64-based systems 1.001
    • Windows Server 2008 R2 for x64-based Systems Service Pack 1 1.001
    • Windows Server 2008 R2 for x64-based Systems Service Pack 1 (Server Core installation) 1.001
    • Windows Server 2008 for 32-bit Systems Service Pack 2 1.001
    • Windows Server 2008 for 32-bit Systems Service Pack 2 (Server Core installation) 1.001
    • Windows Server 2008 for x64-based Systems Service Pack 2 1.001
    • Windows Server 2008 for x64-based Systems Service Pack 2 (Server Core installation) 1.001
    • Windows Server 2012 1.001
    • Windows Server 2012 (Server Core installation) 1.001
    • Windows Server 2012 R2 1.001
    • Windows Server 2012 R2 (Server Core installation) 1.001

Vendor assessments

Microsoft

Microsoft's page for this CVE →

Impact
Remote Code Execution
Exploited
Yes
Publicly disclosed
Yes
Exploitability
Exploitation Detected

Timeline

  1. 2021-11-03 Added to CISA KEV
  2. 2026-10-02 Threatist record created from CVE-2021-40444
  3. 2026-10-03 Alias added: GHSA-2h32-fhf6-xhh5

References

Exploit 2

Patch 2

Advisory 1

  • TI-2017-06077 Microsoft Windows XP SP3, Windows XP x64 XP2, Windows Server 2003 SP2, Windows Vista… KEVCVSS 3.1CRITICAL 9.8
  • TI-2025-24062 Windows SMB Client Elevation of Privilege Vulnerability KEVCVSS 3.1HIGH 8.8
  • TI-2025-24042 Internet Shortcut Files Remote Code Execution Vulnerability KEVCVSS 3.1HIGH 8.8
  • TI-2024-32708 Windows Task Scheduler Elevation of Privilege Vulnerability KEVCVSS 3.1HIGH 8.8
  • TI-2024-29106 Windows MSHTML Platform Spoofing Vulnerability KEVCVSS 3.1HIGH 8.8
  • TI-2024-19802 Windows MSHTML Platform Security Feature Bypass Vulnerability KEVCVSS 3.1HIGH 8.8
See all 1229 →

Sources

This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences