KEV · Actively exploited
CVE-2023-21529
HIGH 8.8
Vendor bulletin scale — NVD CVSS pending
KEV
Microsoft Exchange Server Remote Code Execution Vulnerability
EPSS
62.10%
exploit likely
percentile 99.1%
CISA Known Exploited Vulnerability
- Added to KEV
- 2026-04-13
- Remediation deadline
- 2026-04-27
- 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.
- Ransomware
- Yes, known ransomware campaign