CVE-2023-21529 — Microsoft Exchange Server Deserialization of Untrusted Data Vulnerability
2026-04-13 • CISA Known Exploited Vulnerability
[event] Microsoft Exchange Server contains a deserialization of untrusted data that allows an authenticated attacker to achieve remote code execution.
> AFFECTED SOFTWARE
| Field | Value |
|---|---|
| Vendor | Microsoft |
| Product | Exchange Server |
| CWE | CWE-502 |
| CVE ID | CVE-2023-21529 |
| Date Added | 2026-04-13 |
| Due Date | 2026-04-27 |
| Ransomware Campaign | Known — this vulnerability has been leveraged in ransomware campaigns |
> MITIGATION
Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.
Due Date: 2026-04-27