Exploited· due 2021-11-179.8criticalCriticalused in ransomware

CVE-2021-21985

Vmware Vcenter Server

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.

Exploitation status

CISA has confirmed this is being exploited in the wild. That is an observation of real attacks, not a prediction.
It is known to have been used in ransomware campaigns.
US federal civilian agencies are required to remediate it by 2021-11-17. That deadline does not bind private companies, but it is a reasonable benchmark for how urgently CISA views it.
A vendor advisory or patch reference has been published.

Required action

Apply updates per vendor instructions.

CISA’s wording, unedited.

What the metrics mean

It is reachable over a network, without needing local access.
For an attacker who can reach it, no special conditions are needed to exploit it.
To exploit it, no account is needed.
Beyond that, no action by a user is required.

Scoring

CVSS: 9.8 (v3.1)
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Weakness: CWE-918
Assigned by: security@vmware.com

Dates

Published: 2021-05-26
Last modified: 2026-08-12
Added to KEV: 2021-11-03
Remediation due: 2021-11-17
Sources: CISA KEV, NVD

Affected products

Vmware Vcenter Server6.5, 6.7, 7.0
Vmware Cloud Foundation3.0 - 3.10.2.1, 4.0 - 4.2.1

As listed in the NVD configuration data. Not a statement about your estate.