CVE-2021-42321

Known Exploited Public Exploit

Microsoft Exchange Server Remote Code Execution Vulnerability

Description

Microsoft Exchange Server Remote Code Execution Vulnerability

8.8

CVSS

Severity: High

CVSS 3.1 •

CVSS 2.0 •

EPSS 93.51% Top 5%

KEV Since

Vendor Advisory microsoft.com

Affected: Microsoft Microsoft Exchange Server 2016 Cumulative Update 21

Affected: Microsoft Microsoft Exchange Server 2019 Cumulative Update 10

Affected: Microsoft Microsoft Exchange Server 2016 Cumulative Update 22

Affected: Microsoft Microsoft Exchange Server 2019 Cumulative Update 11

References

Link	Tags
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-42321	patch vendor advisory
http://packetstormsecurity.com/files/166153/Microsoft-Exchange-Server-Remote-Code-Execution.html	exploit vdb entry third party advisory
http://packetstormsecurity.com/files/168131/Microsoft-Exchange-Server-ChainedSerializationBinder-Remote-Code-Execution.html	exploit vdb entry third party advisory

Frequently Asked Questions

What is the severity of CVE-2021-42321?: CVE-2021-42321 has been scored as a high severity vulnerability.
How to fix CVE-2021-42321?: To fix CVE-2021-42321, make sure you are using an up-to-date version of the affected component(s) by checking the vendor release notes. As for now, there are no other specific guidelines available.
Is CVE-2021-42321 being actively exploited in the wild?: It is confirmed that CVE-2021-42321 is actively exploited. Be extra cautious if you are using vulnerable components. According to its EPSS score, there is a ~94% probability that this vulnerability will be exploited by malicious actors in the next 30 days.
What software or system is affected by CVE-2021-42321?: CVE-2021-42321 affects Microsoft Microsoft Exchange Server 2016 Cumulative Update 21, Microsoft Microsoft Exchange Server 2019 Cumulative Update 10, Microsoft Microsoft Exchange Server 2016 Cumulative Update 22, Microsoft Microsoft Exchange Server 2019 Cumulative Update 11.

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