known ransomware use

VMware vCenter Server Improper Input Validation Vulnerability

Added to KEV
2021-11-03
Federal due date
2021-11-17
Vendor
VMware
Product
vCenter Server
EPSS
100.0th percentile (score 0.944, as of 2026-06-08)
NVD CVSS v3.1
Ransomware use
Known
Upstream
https://nvd.nist.gov/vuln/detail/CVE-2021-21985

CISA short description

VMware vSphere Client contains an improper input validation vulnerability in the Virtual SAN Health Check plug-in, which is enabled by default in vCenter Server, which allows for 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.