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Servers and applications

CVE-2023-21529

Microsoft Exchange Server Remote Code Execution Vulnerability

Actively exploited: CISA added it to its Known Exploited Vulnerabilities catalog on 13 Apr 2026.

Severity
High 8.8
Published
14 Feb 2023
Last changed
19 Aug 2026
Added to UpHeron
1 Nov 2026
Sources
NVD

Affected software

SoftwareAffected versions
Microsoft Exchange ServerServers and applications · cpe:a:microsoft:exchange_server
  • Version 2013-cumulative_update_23
  • Version 2016-cumulative_update_23
  • Version 2019-cumulative_update_11
  • Version 2019-cumulative_update_12

Known exploited

CISA name
Microsoft Exchange Server Deserialization of Untrusted Data Vulnerability
Required action
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Due for US agencies
27 Apr 2026
Used in ransomware
Yes, known

References

  • NVD https://nvd.nist.gov/vuln/detail/CVE-2023-21529
  • CVE.org https://www.cve.org/CVERecord?id=CVE-2023-21529