Microsoft Exchange Server Deserialization of Untrusted Data Vulnerability

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• NewsExploited · CISA KEVKnown ransomware useMicrosoft · Exchange Server

  Microsoft Exchange Server Deserialization of Untrusted Data Vulnerability

  CVE-2023-21529

  Microsoft Exchange Server contains a deserialization of untrusted data that allows an authenticated attacker to achieve remote code execution.

  CISA's required action · due 27 Apr 2026 for U.S. federal civilian agencies

  Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

  Cited by CISA: msrc.microsoft.com · nvd.nist.gov

  Added to KEV 13 Apr 2026 · Source checked 4 Nov 2026, 16:35 UTC · CISA KEV entry

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