VulnerabilityALERT Critical

CVE-2023-21529: Microsoft Exchange Server Deserialization of Untrusted Data Vulnerability

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

Impact

CISA lists CVE-2023-21529 as known exploited in the wild for Microsoft Exchange Server. Ransomware campaign use: Known. Federal remediation due date: 2026-04-27.

Recommended 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.

Published: 4/13/2026, 12:00:00 AMSource: CISA Known Exploited Vulnerabilities CatalogTags: CVE-2023-21529, Microsoft, Exchange Server, CISA KEV, CWE-502