Critical (9.8) in VMware vCenter Server. In CISA KEV since 2021-11-03, with known ransomware use. EPSS 100% chance of exploitation in the next 30 days.
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.
Severity
CVSS 3.1
9.8 critical
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS
100% chance of exploitation in the next 30 days; higher than 99% of CVEs (scores of 2026-10-31)
CISA KEV
listed 2021-11-03, due 2021-11-17, known ransomware use