Vulnerability identifier: #VU56377

Vulnerability risk: Critical

CVSSv3.1: 8.4 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:H/RL:O/RC:C]

CVE-ID: CVE-2021-40444

CWE-ID: CWE-94

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
Windows
Operating systems & Components / Operating system
Windows Server
Operating systems & Components / Operating system
Microsoft Internet Explorer
Client/Desktop applications / Web browsers

Vendor: Microsoft

Description

The vulnerability allows a remote attacker to execute arbitrary code on the target system.

The vulnerability exists due to improper input validation within the MSHTML component. A remote attacker can create a specially crafted Office document with a malicious ActiveX control inside, trick the victim into opening the document and execute arbitrary code on the system.

Successful exploitation of this vulnerability may result in complete compromise of vulnerable system.

Note, the vulnerability is being actively exploited in the wild.

Mitigation
Install update from vendor's website.

Vulnerable software versions

Windows: 10 - 10 S, 8.1 - 8.1 RT

Windows Server: 2008 - 2019 2004

Microsoft Internet Explorer: 11

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External links
http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40444

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote non-authenticated attacker via the Internet.

Is there known malware, which exploits this vulnerability?

Yes. This vulnerability is being exploited in the wild.