CVE-2021-42321

high

Description

Microsoft Exchange Server Remote Code Execution Vulnerability

From the Tenable Blog

Microsoft’s November 2021 Patch Tuesday Addresses 55 CVEs (CVE-2021-42321)

Microsoft’s November 2021 Patch Tuesday Addresses 55 CVEs (CVE-2021-42321)

Published: 2021-11-09

Microsoft addresses 55 CVEs in its November 2021 Patch Tuesday release, including two zero-day vulnerabilities that have been exploited in the wild.

References

https://www.microsoft.com/en-us/security/blog/2023/03/24/guidance-for-investigating-attacks-using-cve-2023-23397/

https://www.tenable.com/cyber-exposure/2021-threat-landscape-retrospective

https://www.tenable.com/blog/microsoft-s-november-2021-patch-tuesday-addresses-55-cves-cve-2021-42321

https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-42321

https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-42321

https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-42321

http://packetstormsecurity.com/files/168131/Microsoft-Exchange-Server-ChainedSerializationBinder-Remote-Code-Execution.html

http://packetstormsecurity.com/files/166153/Microsoft-Exchange-Server-Remote-Code-Execution.html

Details

Source: Mitre, NVD

Published: 2021-11-10

Updated: 2026-08-19

Known Exploited Vulnerability (KEV)

Risk Information

CVSS v2

Base Score: 6.5

Vector: CVSS2#AV:N/AC:L/Au:S/C:P/I:P/A:P

Severity: Medium

CVSS v3

Base Score: 8.8

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

Severity: High

EPSS

EPSS: 0.91737