CVE-2021-42321

HighCVSS 8.8/10Known exploited (CISA KEV)Last modified Aug 19, 2026

Description

Microsoft Exchange Server Remote Code Execution Vulnerability

Metrics

CVSS 3.1 8.8/10CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected software

Vendor	Product	Versions
Microsoft	Microsoft Exchange Server 2016 Cumulative Update 21	>= 15.01.0, < 15.01.2308.020
Microsoft	Microsoft Exchange Server 2016 Cumulative Update 22	>= 15.0.0, < 15.01.2375.017
Microsoft	Microsoft Exchange Server 2019 Cumulative Update 10	>= 15.02.0, < 15.02.0792.019
Microsoft	Microsoft Exchange Server 2019 Cumulative Update 11	>= 15.02.0, < 15.02.0986.014

References

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-42321Patch, Vendor Advisory
http://packetstormsecurity.com/files/166153/Microsoft-Exchange-Server-Remote-Code-Execution.htmlExploit, Third Party Advisory, VDB Entry
http://packetstormsecurity.com/files/168131/Microsoft-Exchange-Server-ChainedSerializationBinder-Remote-Code-Execution.htmlExploit, Third Party Advisory, VDB Entry
https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-42321Patch, Vendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-42321US Government Resource

Timeline

Published: Nov 10, 2021
Last modified: Aug 19, 2026
Added to CISA KEV: Nov 17, 2021
NVD status: Analyzed

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