November 3, 2021 · Applied Cybernetics Group
CVE-2021-34523 — Microsoft Exchange Server
known ransomware use
Microsoft Exchange Server Privilege Escalation Vulnerability
- Added to KEV
2021-11-03- Federal due date
2021-11-17- Vendor
- Microsoft
- Product
- Exchange Server
- EPSS
- 99.9th percentile (score 0.940, as of
2026-06-08) - NVD CVSS v3.1
- —
- Ransomware use
- Known
- Upstream
- https://nvd.nist.gov/vuln/detail/CVE-2021-34523
CISA short description
Microsoft Exchange Server contains an unspecified vulnerability that allows for privilege escalation.
Required action
Apply updates per vendor instructions.