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8.8
CVSS
High

CVE-2021-42321

PUBLISHED

Microsoft Exchange Server Remote Code Execution Vulnerability

Exploited in the wild Used in malware Remote Low complexity No user interaction
Vendor
Microsoft
Product
Microsoft Exchange Server 2016 Cumulative Update 21, Microsoft Exchange Server 2019 Cumulative Update 10, Microsoft Exchange Server 2016 Cumulative Update 22, Microsoft Exchange Server 2019 Cumulative Update 11
Published
Nov 10, 2021
EPSS
—

Description

Microsoft Exchange Server Remote Code Execution Vulnerability

cisa malware ransomware metasploit microsoft

CVSS scores

CVSS v3.1 8.8 High

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H/E:U/RL:O/RC:C

Exploitation status

Exploited in the wild

Recorded 2021-11-17 00:00:00 UTC · Source

Used in malware

Recorded 2021-11-17 00:00:00 UTC · Source

SSVC decision points

Exploitation
active
Automatable
No
Technical impact
total

References

Known exploited vulnerability sources

Catalogues that list this CVE as a known exploited vulnerability.

Source Added
CISA Nov 17, 2021
CISA Nov 17, 2021

Scanner integrations

Scanner Reference Detected
Metasploit https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/windows/http/exchange_chainedserializationbinder_rce.rb Apr 28, 2025

Potential proof of concepts

These PoCs are unverified and could contain malware. Use at your own risk.

7BitsTeam/exch_CVE-2021-42321

github · Created 2022-10-08 13:00:23 UTC · 10 stars

DarkSprings/CVE-2021-42321

github · Created 2021-11-23 02:26:26 UTC · 85 stars

Microsoft Exchange Server Poc

Timeline

  • CVE ID Reserved

  • CVE Published to Public

  • Exploit Used in Malware

  • Added to KEVIntel

  • Added to KEVIntel

  • Detected by Metasploit