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CVE-2021-42321
HIGH8.8
CISA KEV
Published 2021-11-10 · Updated 2026-08-19 · Source secure@microsoft.com
Description
Microsoft Exchange Server Remote Code Execution Vulnerability
CVSS vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
CISA Known-Exploited Vulnerability
Product: Microsoft — Exchange
Name: Microsoft Exchange Server Remote Code Execution Vulnerability
Date added: 2021-11-17 · Due: 2021-12-01
USED IN RANSOMWARE
Required action: Apply updates per vendor instructions.
References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2021-42321
- http://packetstormsecurity.com/files/166153/Microsoft-Exchange-Server-Remote-Code-Execution.html
- http://packetstormsecurity.com/files/168131/Microsoft-Exchange-Server-ChainedSerializationBinder-Remote-Code-Execution.html
- https://portal.msrc.microsoft.com/en-US/security-guidance/advisory/CVE-2021-42321
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-42321

