CVE-2021-21972 remediation guide

VMware vCenter Server

The vSphere Client (HTML5) contains a remote code execution vulnerability in a vCenter Server plugin. 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. This affects VMware vCenter Server (7.x before 7.0 U1c, 6.7 before 6.7 U3l and 6.5 before 6.5 U3n) and VMware Cloud Foundation (4.x before 4.2 and 3.x before 3.10.1.2).

Open CVE record

ProductVMware vCenter Server

Affected versions7.x before 7.0 U1c, 6.7 before 6.7 U3l, 6.5 before 6.5 U3n, 4.x before 4.2, 3.x before 3.10.1.2, >= 3.0 < 3.10.1.2, >= 4.0 < 4.2, 6.5, 6.7, 7.0

Fixed versions3.10.1.2, 4.2

Priority basisImmediate · CVSS 9.8 · EPSS 99.5%

Identify the affected asset

Confirm whether VMware vCenter Server is installed, record the deployed version and installation path, and identify exposed interfaces.

Record the product name, package or appliance identifier, and installed version.
Identify internet-facing, administrative, API, and internal access paths.
Preserve the pre-change configuration and relevant service logs.

Validate the affected-version match

Compare the deployed version with the affected range: 7.x before 7.0 U1c, 6.7 before 6.7 U3l, 6.5 before 6.5 U3n, 4.x before 4.2, 3.x before 3.10.1.2, >= 3.0 < 3.10.1.2, >= 4.0 < 4.2, 6.5, 6.7, 7.0. Treat incomplete inventory results as unresolved.

Prioritize with independent signals

CISA has listed this vulnerability in the Known Exploited Vulnerabilities catalog. Combine this signal with asset criticality, exposure, compensating controls, and business impact.

Apply supported remediation

Apply updates per vendor instructions.

Verify the result

Confirm the resulting version, service health, authentication and access paths, monitoring coverage, and relevant security logs.

Confirm the expected version and package state.
Run a functional health check for critical service paths.
Review authentication, error, application, and security monitoring logs.
Reassess exposure if the supported fix cannot be applied.

Operational boundary

This page does not replace the vendor advisory, support contract, change-management process, or recovery plan. Do not infer that an asset is unaffected from an incomplete inventory query or a missing fixed-version field.