Vulnerability identifier: #VU51174

Vulnerability risk: High

CVSSv3.1: 7.9 [CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-26412

CWE-ID: CWE-20

Exploitation vector: Network

Exploit availability: No

Vulnerable software:
Microsoft Exchange Server
Server applications / Mail servers

Vendor: Microsoft

Description

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

The vulnerability exists due to insufficient validation of user-supplied input. A remote attacker can send specially crafted data to the Exchange server and execute arbitrary code on the system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Microsoft Exchange Server: 2013 RTM 15.00.0516.032 - 2013 Cumulative Update 23 15.00.1497.002, 2019 RTM 15.02.0221.012 - 2019 Cumulative Update 8 15.02.0792.003, 2016 RTM 15.01.0225.042 - 2016 Cumulative Update 19 15.01.2176.002

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External links
http://msrc-blog.microsoft.com/2021/03/02/multiple-security-updates-released-for-exchange-server
http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-26412

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Q & A

Can this vulnerability be exploited remotely?

Yes. This vulnerability can be exploited by a remote authenticated privileged user via the Internet.

Is there known malware, which exploits this vulnerability?

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