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CISA KEV · Known exploitedHigh

CVE-2021-40444

Microsoft MSHTML

<p>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.</p> <p>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 o...

CVSS
7.8
EPSS
97.2%
99.9% percentile
CISA KEV
Listed
Published
2021.09.15
PRIORITY ASSESSMENT

Immediate review

CISA has listed this vulnerability in the Known Exploited Vulnerabilities catalog.

Known exploitationConfirmed by CISA KEV
Exploit probability97.2%
Technical severityCVSS 7.8

Vulnerability overview

<p>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.</p> <p>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 o...

Affected product and versions

Product
Microsoft MSHTML
Affected versions
10.0.0, 6.1.0, 6.3.0, 6.0.0, 6.2.0, < 10.0.10240.19060, < 10.0.14393.4651, < 10.0.17763.2183, < 10.0.18363.1801, < 10.0.19041.1237, < 10.0.19042.1237, < 10.0.19043.1237, r2, < 10.0.20348.230
Fixed versions
10.0.10240.19060, 10.0.14393.4651, 10.0.17763.2183, 10.0.18363.1801, 10.0.19041.1237, 10.0.19042.1237, 10.0.19043.1237, 10.0.20348.230

Recommended response sequence

Confirm exposure before applying a vendor-supported change.

Full remediation guide
CISA required action

Apply updates per vendor instructions.

Due date: 2021.11.17
  1. 1
    Identify

    Confirm that Microsoft MSHTML and an affected version are present.

  2. 2
    Prioritize

    Combine exploitation signals with asset exposure and business criticality.

  3. 3
    Remediate

    Follow the vendor advisory or supported update path and preserve rollback options.

  4. 4
    Verify

    Recheck the version, service health, access paths, and relevant logs.

Technical data

CVSS vector
CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H
CWE
CWE-22
KEV added
2021.11.03
Ransomware use
확인됨
CVE-2021-40444 — Microsoft MSHTML | SECUFOCUS NOW