⚠ Actively exploited
Added to CISA KEV on 2026-04-13. Federal agencies required to patch by 2026-04-27. 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..

CVE-2023-21529

CWE-502 — Deserialization of Untrusted Data8 documents8 sources
Severity
8.8HIGH
EPSS
36.7%
top 2.86%
CISA KEV
KEV
Added 2026-04-13
Due 2026-04-27
Exploit
No known exploits
Affected products
5
Microsoft Microsoft Exchange Server 2013 Cumulative Update 23Microsoft Microsoft Exchange Server 2016 Cumulative Update 23Microsoft Microsoft Exchange Server 2019 Cumulative Update 11+2 more
Timeline
PublishedFeb 14
KEV addedApr 13
KEV dueApr 27
CISA 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.

Description

Microsoft Exchange Server Remote Code Execution Vulnerability

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HExploitability: 2.8 | Impact: 5.9

Affected Packages5 packages

▶NVDmicrosoft/exchange_server2013, 2016, 2019+2

Patches

Patch: msrc.microsoft.com ↗Patch: msrc.microsoft.com ↗

🔴Vulnerability Details

4
VulDB
Microsoft Exchange Server 2013 CU23/2016 CU23/2019 CU11/2019 CU12 privilege escalation↗2026-04-13
▶
GHSA
GHSA-hjxr-gv9h-rjxc: Microsoft Exchange Server Remote Code Execution Vulnerability↗2023-02-14
▶
CVEList
Microsoft Exchange Server Remote Code Execution Vulnerability↗2023-02-14
▶
VulnCheck
Microsoft Exchange Server Deserialization of Untrusted Data↗2023
▶

📋Vendor Advisories

2
CISA
Microsoft Exchange Server Deserialization of Untrusted Data Vulnerability↗2026-04-13
▶
Microsoft
Microsoft Exchange Server Remote Code Execution Vulnerability↗2023-02-14
▶