CVE-2021-42321

Microsoft Exchange Server Remote Code Execution Vulnerability

Published Nov 9, 2021 · updated Aug 19, 2026 · microsoft exchange server

An authenticated attacker could leverage improper validation in cmdlet arguments within Microsoft Exchange and perform remote code execution.

Timeline

Detection, updates, and resolution for this record.

Nov 9, 2021 · Catalog
Detected
An authenticated attacker could leverage improper validation in cmdlet arguments within Microsoft Exchange and perform remote code execution.
Nov 17, 2021 · CISA KEV
Known exploited
Apply updates per vendor instructions.
Dec 1, 2021 · CISA KEV
Remediation due
Apply updates per vendor instructions.
Aug 19, 2026 · Catalog
Updated
An authenticated attacker could leverage improper validation in cmdlet arguments within Microsoft Exchange and perform remote code execution.

Apply updates per vendor instructions.

CISA due date Dec 1, 2021

CISA KEVCVE-2021-42321
An authenticated attacker could leverage improper validation in cmdlet arguments within Microsoft Exchange and perform remote code execution.
cisa.gov
CVE.orgCVE-2021-42321
Official CVE identifier
cve.org
FIRST EPSSCVE-2021-42321
30-day exploitation probability 91.7%
first.org
Metasploit Modulesexploit_windows/http/exchange_chainedserializationbinder_rce
Public module reference (excellent). Module source is not copied into this catalog.
rapid7.com
NIST NVDCVE-2021-42321
Microsoft Exchange Server Remote Code Execution Vulnerability
nvd.nist.gov
Packet Storm Securityhttp://packetstormsecurity.com/files/166153/Microsoft-Exchange-Server-Remote-Code-Execution.html
Packet Storm link already published on the finding.
packetstormsecurity.com
Packet Storm Securityp://packetstormsecurity.com/files/168131/Microsoft-Exchange-Server-ChainedSerializationBinder-Remote-Code-Execution.html
Packet Storm link already published on the finding.
packetstormsecurity.com