Vulnerability identifier: #VU50401

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-2021-26411

CWE-ID: CWE-415

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
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 a boundary error when processing ".mht" files. A remote attacker can trick the victim to visit a specially crafted webpage, trigger a double free error and execute arbitrary code on the target 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

Microsoft Internet Explorer: 9 - 11

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External links
http://enki.co.kr/blog/2021/02/04/ie_0day.html
http://twitter.com/dnpushme/status/1357264755333816320
http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26411

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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.