High severity · published Feb 14, 2023
CVE-2023-21529
Microsoft Exchange Server Remote Code Execution Vulnerability
RansomwareIn wildKEV
8.8
CVSS
59.3%
EPSS
Yes
On KEV
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Attack vector
Network
Complexity
Low
Privileges
Low
User interaction
None
Confidentiality
High
Integrity
High
Availability
High
Scope
Unchanged
Exploitation
Is it being used?
Exploit prediction (EPSS)59.3% · higher than 99% of CVEs
Exploited in the wildYes
CISA KEVListed Apr 13, 2026
Federal remediation dueApr 27, 2026
Ransomware campaign useKnown
Affected products
Which versions
ES
Exchange Server · Microsoft
2013; 2016; 2019; 2019 · source: NVD, KEV
ME
Microsoft Exchange Server 2013 Cumulative Update 23 · Microsoft
15.00.0 before 15.00.1497.047 · source: vendor
ME
Microsoft Exchange Server 2016 Cumulative Update 23 · Microsoft
15.01.0 before 15.01.2507.021 · source: vendor
ME
Microsoft Exchange Server 2019 Cumulative Update 11 · Microsoft
15.02.0 before 15.02.0986.041 · source: vendor
ME
Microsoft Exchange Server 2019 Cumulative Update 12 · Microsoft
15.02.0 before 15.02.1118.025 · source: vendor
In the news
VulnerabilityHigh
[CISA KEV] CVE-2023-21529: Microsoft Exchange Server - 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.
ESExchange ServerCVE-2023-21529
Apr 13, 2026·CISA KEV
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2023-21529
CVE.org
https://www.cve.org/CVERecord?id=CVE-2023-21529
CISA KEV catalogue
https://www.cisa.gov/known-exploited-vulnerabilities-catalog
vendor-advisory
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529
More from Exchange Server
9.8
CVE-2024-21410
Microsoft Exchange Server Elevation of Privilege Vulnerability
9.1
CVE-2021-34473
Microsoft Exchange Server Remote Code Execution Vulnerability
9.1
CVE-2021-26855
Microsoft Exchange Server Remote Code Execution Vulnerability
9.0
CVE-2021-34523
Microsoft Exchange Server Elevation of Privilege Vulnerability
8.8
CVE-2022-41080
Microsoft Exchange Server Elevation of Privilege Vulnerability