CVE-2021-21985: VMware vCenter Server Improper Input Validation Vulnerability

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: yes — in CISA KEV since 2021-11-03
EPSS: 100.0% probability of exploitation in the next 30 days
Public exploit or detection template: yes
Published: 2021-05-26 · updated 2026-08-12
Weakness: CWE-918

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.

Affected products

VMware Cloud Foundation: from 3.0 before 3.10.2.1; from 4.0 before 4.2.1 — fixed in 3.10.2.1, 4.2.1
VMware vCenter Server: 6.5, 6.5-a, 6.5-b, 6.5-c, 6.5-d, 6.5-e (+45)
VMware vCenter Server and VMware Cloud Foundation: VMware vCenter Server (7.x before 7.0 U2b, 6.7 before 6.7 U3n, 6.5 before 6.5 U3p) and VMware Cloud Foundation (4.x before 4.2.1, 3.x before 3.10.2.1)

How to fix

Upgrade to a fixed version: VMware Cloud Foundation 3.10.2.1, 4.2.1. Check the vendor advisory for mitigations.

References

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