Microsoft Exchange Server Deserialization of Untrusted Data Vulnerability
Description
Microsoft Exchange Server contains a deserialization of untrusted data that allows an authenticated attacker to achieve remote code execution.
What to do
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
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Details
- Vendor
- Microsoft
- Product
- Exchange Server
- CVE
- CVE-2023-21529
- Affected versions
- Microsoft Exchange Server 2013 Cumulative Update 23 15.00: from 15.00.0 to 15.00.1497.047 (excluded) — fixed in 15.00.1497.047
Microsoft Exchange Server 2016 Cumulative Update 23 15.01: from 15.01.0 to 15.01.2507.021 (excluded) — fixed in 15.01.2507.021
Microsoft Exchange Server 2019 Cumulative Update 11 15.02: from 15.02.0 to 15.02.0986.041 (excluded) — fixed in 15.02.0986.041
Microsoft Exchange Server 2019 Cumulative Update 12 15.02: from 15.02.0 to 15.02.1118.025 (excluded) — fixed in 15.02.1118.025 (from the advisory and NVD; check the exact builds in the official advisory) - CVSS score
- 8.8
- Actively exploited
- Yes, listed in the CISA Known Exploited Vulnerabilities catalog
- CISA due date
- April 27, 2026 (deadline for US federal agencies: a good benchmark for you too)
- Source
- CISA KEV – original advisory
- Published
- April 13, 2026
The description and the recommended action are quoted from the public advisory; severity, exploitation status and affected versions are compiled automatically from public sources and may contain errors. The vendor's original advisory prevails: check it before taking action. This information is provided without warranty and does not replace a professional assessment.