Vulnerability identifier: #VU57261

Vulnerability risk: High

CVSSv3.1: 7.7 [CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-40486

CWE-ID: CWE-416

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Microsoft SharePoint Server
Server applications / Application servers
Microsoft Office Web Apps Server
Server applications / Application servers
Microsoft Office
Client/Desktop applications / Office applications
Microsoft Word
Client/Desktop applications / Office applications
Office Online Server
Server applications / Other server solutions

Vendor: Microsoft

Description

The vulnerability allows a remote attacker to compromise vulnerable system.

The vulnerability exists due to a use-after-free error when processing DOC files in Microsoft Word. A remote attacker can trick the victim to open a specially crafted document, trigger a use-after-free error and execute arbitrary code on the system.

Successful exploitation of the vulnerability may allow an attacker to compromise vulnerable system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Microsoft SharePoint Server: 2013 - 2019

Microsoft Office: 2019, 2013 - 2013 RT

Office Online Server : 2016

Microsoft Word:

Microsoft Office Web Apps Server: 2013 Service Pack 1

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External links
http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-40486
http://www.zerodayinitiative.com/advisories/ZDI-21-1158/

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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?

No. We are not aware of malware exploiting this vulnerability.