November 3, 2021 · Applied Cybernetics Group
CVE-2021-21985 — VMware vCenter Server
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 1.000, as of
2026-09-16) - NVD CVSS v3.1
- 9.8 (CRITICAL)
- 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.
NVD description
The vSphere Client (HTML5) contains a remote code execution vulnerability due to lack of input validation in the Virtual SAN Health Check plug-in which is enabled by default in vCenter Server. A malicious actor with network access to port 443 may exploit this issue to execute commands with unrestricted privileges on the underlying operating system that hosts vCenter Server.