Microsoft Exchange Server Remote Code Execution Vulnerability

Added to KEV
2021-11-03
Federal due date
2022-05-03
Vendor
Microsoft
Product
Exchange Server
EPSS
99.7th percentile (score 0.920, as of 2026-06-08)
NVD CVSS v3.1
Ransomware use
Unknown
Upstream
https://nvd.nist.gov/vuln/detail/CVE-2020-17144

CISA short description

Microsoft Exchange Server improperly validates cmdlet arguments which allow an attacker to perform remote code execution.

Required action

Apply updates per vendor instructions.

EPSS percentile is the FIRST.org exploit-probability ranking as of the date noted above; it moves daily. CVSS reflects NVD's analysis at time of publication.