#VU53085 Security features bypass in Microsoft Exchange Server - CVE-2021-31207

Vulnerability identifier: #VU53085

Vulnerability risk: Low

CVSSv4.0: 7.5 [CVSS:4.0/AV:N/AC:L/AT:P/PR:H/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N/E:A/U:Clear]

CVE-ID: CVE-2021-31207

CWE-ID: CWE-254

Exploitation vector: Network

Exploit availability: Yes

Vulnerable software:
Microsoft Exchange Server
Server applications / Mail servers

Vendor: Microsoft

Description

The vulnerability allows a remote user to bypass authentication process.

The vulnerability exists due to security feature bypass issue in Microsoft Exchange Server. A remote administrator can gain full access to target system.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Microsoft Exchange Server: 2013 Cumulative Update 23 15.00.1497.002, 2016 Cumulative Update 19 15.01.2176.002 - 2016 Cumulative Update 20 15.01.2242.004, 2019 Cumulative Update 8 15.02.0792.003 - 2019 Cumulative Update 9 15.02.0858.005

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External links
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-31207

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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?

Yes. This vulnerability is being exploited in the wild.