Vulnerability identifier: #VU57254

Vulnerability risk: Medium

CVSSv3.1: 6.5 [CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H/E:U/RL:O/RC:C]

CVE-ID: CVE-2021-34453

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 perform a denial of service (DoS) attack.

The vulnerability exists due to insufficient validation of user-supplied input. A remote attacker can send  specially crafted input to the server and perform a denial of service (DoS) attack.

Mitigation
Install updates from vendor's website.

Vulnerable software versions

Microsoft Exchange Server: 2019 RTM 15.02.0221.012 - 2019 Cumulative Update 11 15.02.0986.005, 2016 RTM 15.01.0225.042 - 2016 Cumulative Update 22 15.01.2375.007

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External links
http://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-34453

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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.