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.

Added to CISA’s Known Exploited Vulnerabilities catalog on 2026-04-13. Required action per CISA: 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 date: 2026-04-27.

This is an auto-synced KEV catalog record pending a full 0dayNews write-up — see CISA’s KEV catalog and the NVD record linked above for primary sources.