#VU51174 Input validation error in Microsoft Exchange Server - CVE-2021-26412

Vulnerability identifier: #VU51174

Vulnerability risk: High

CVSSv4.0: 2.5 [CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:N/VC:N/VI:N/VA:N/SC:H/SI:H/SA:H/E:U/U:Amber]

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 Cumulative Update 2 15.00.0712.024 - 2013 RTM 15.00.0516.032, 2016 Cumulative Update 1 15.01.0396.030 - 2016 RTM 15.01.0225.042, 2019 Cumulative Update 1 15.02.0330.005 - 2019 RTM 15.02.0221.012

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External links
https://msrc-blog.microsoft.com/2021/03/02/multiple-security-updates-released-for-exchange-server
https://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.