CVE detail
CVE-2023-21529: Microsoft Exchange Server Deserialization of Untrusted Data Vulnerability
Source: CISA Known Exploited Vulnerabilities catalog · back to feed
Vendor / product
Microsoft · Exchange Server
- Date added (KEV)
- Apr 13, 2026
- CISA due date
- Apr 27, 2026
- Ransomware campaign use
- Known
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.
Scorifya interpretation
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Plain English
Technical detail
From CISA
Microsoft Exchange Server contains a deserialization of untrusted data that allows an authenticated attacker to achieve remote code execution.
https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529 ; https://nvd.nist.gov/vuln/detail/CVE-2023-21529
See what attackers can see on your domain
This vulnerability is on CISA's Known Exploited Vulnerabilities list, so it is being exploited in the wild right now, including in ransomware campaigns. Scorifya can't test for Microsoft directly, but in about 30 seconds it shows what your own domain exposes publicly across TLS, security headers, DNS, and cookies: the surface attackers probe first.
SOC 2 compliance
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See Scorifya Controls →References
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529PatchVendor Advisory
- https://msrc.microsoft.com/update-guide/vulnerability/CVE-2023-21529PatchVendor Advisory
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2023-21529US Government Resource
- 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/Technical Description
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