high8.8Known exploited
CVE-2023-21529
Microsoft Exchange Server Deserialization of Untrusted Data Vulnerability
Exploited in the wild
This vulnerability is on the CISA Known Exploited Vulnerabilities list, added 2026-04-13. Federal due date: 2026-04-27.
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Impact
Microsoft Exchange Server contains a deserialization of untrusted data that allows an authenticated attacker to achieve remote code execution.
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Microsoft | Exchange Server | Versions 2013, 2016, 2019 |
Weakness classification
References
- NVD record
- CVE.org record
- CISA KEV catalog
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-21529
- https://www.microsoft.com/en-us/security/blog/2026/04/06/storm-1175-focuses-gaze-on-vulnerable-web-facing-assets-in-high-tempo-medusa-ransomware-operations/