CVE-2021-21972

CRITICAL
9.8
CVSS Score
Published: February 24, 2021 at 04:42 PM UTC
Updated: August 12, 2026 at 05:28 AM UTC
2 products affected across 1 vendorCloud FoundationvCenter Server

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Severity
CRITICAL9.8
Exploitation
CISA KEV
Exploit prediction
EPSS 100%
SSVC
Active

Actively Exploited

CISA Known Exploited Vulnerabilities (KEV) Catalog

EPSS Score99.9%

EPSS (Exploit Prediction Scoring System) estimates a 99.9% chance this CVE is exploited in the wild within the next 30 days — higher than 100% of all CVEs. It complements CVSS: a high EPSS on a mid-severity CVE can still be urgent.

VMware vCenter Server vSphere Client contains a remote code execution vulnerability in a vCenter Server plugin which allows an attacker with network access to port 443 to execute commands with unrestricted privileges on the underlying operating system.

Required Action
Apply updates per vendor instructions.
Ransomware Use
Known
Added to KEV
Nov 3, 2021
Remediation Due
Nov 17, 2021
1809 days overdue

Description

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).

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

3 ≤ v < 3.10.1.23.0 ≤ v < 3.10.1.24 ≤ v < 4.24.0 ≤ v < 4.2
Affected range stops below 3.10.1.2, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.2, so it looks safe — our inference, not a vendor statement
Affected range stops below 6.5, so it looks safe — our inference, not a vendor statement
Affected range stops below 6.7, so it looks safe — our inference, not a vendor statement
Affected range stops below 7.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

SSVC — Action Prioritization

SSVCActiveAutomatableTotal impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

9.8CRITICALCISA-ADP
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
HIGH
Integrity
HIGH
Availability
HIGH
Vector?

Quick Info

StatusANALYZED
CWE
CWE-22

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