CVE-2021-21972: VMware vCenter Server Remote Code Execution Vulnerability

100

Patch now

CRITICAL 9.8EXPLOITEDREMOTEUPGRADEDOWNGRADE

CVE-2021-21972 is a critical-severity flaw (CVSS 9.8) affecting cloud foundation, vcenter server, reported as exploited in the wild. Below: why it ranks where it does, which versions are affected, what to do, and the exact commands.

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

Why this priority

Critical severity
EPSS top 1%: very likely to be exploited
Exploited in the wild (CISA KEV)
Used in ransomware campaigns
Public exploit reference
CISA SSVC: automatable with total technical impact
Remotely exploitable, no login, no user action

A fixed release or distro patch exists.

Risk facts

CVSS score	9.8 (Critical)
Attack vector	Network (remote)
Attack complexity	Low
Privileges needed	None
User interaction	None
EPSS exploit chance	99.9% (top 1%)
CISA exploited list	Yes, fix due 2021-11-17, used in ransomware
Weakness	CWE-22
Published	2021-02-24
Last modified	2026-08-12

Publisher (CNA): VMware · Vendor: vmware

Last updated 2026-08-12 · Sources: CVE Program, NVD, CISA KEV, EPSS and vendor advisories · How we score

Am I affected?

Timeline

2021-02-24 17:15 UTCPublished CVE record published
2021-11-03Exploited Added to the CISA Known Exploited Vulnerabilities list
2021-11-17Deadline CISA due date for US federal agencies to patch
2026-08-12 05:17 UTCUpdated Record last modified

vmware cloud foundation UPGRADE

Affected: >= 3.0 and < 3.10.1.2 · >= 4.0 and < 4.2

Fixed in: 3.10.1.2, 4.2

Safe to downgrade to: a release before 3.0

1. Check installed version

apt-cache policy cloud-foundation || rpm -q cloud-foundation || cloud-foundation --version

2. UPGRADE to 3.10.1.2 (Debian / Ubuntu)

sudo apt update && sudo apt install --only-upgrade cloud-foundation

2. UPGRADE (RHEL / Amazon Linux / Fedora)

sudo dnf upgrade cloud-foundation

Note

Distros often backport fixes without changing the version number. Confirm with the distro advisory or changelog.

3. If no update is available yet, DOWNGRADE to a release before 3.0 (Debian / Ubuntu)

apt-cache madison cloud-foundation sudo apt install cloud-foundation=<VERSION_BEFORE_3.0> sudo apt-mark hold cloud-foundation

3. If no update is available yet, DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list cloud-foundation sudo dnf downgrade cloud-foundation-<VERSION_BEFORE_3.0> sudo dnf versionlock add cloud-foundation

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

vmware vcenter server DOWNGRADE

Affected: 6.5 · 6.5 a · 6.5 b · 6.5 c · 6.5 d · 6.5 e · 6.5 f · 6.5 update1d

Fixed in: no fixed release known

Safe to downgrade to: a release before 6.5

1. Check installed version

apt-cache policy vcenter-server || rpm -q vcenter-server || vcenter-server --version

2. No fixed release: DOWNGRADE to a release before 6.5 (Debian / Ubuntu)

apt-cache madison vcenter-server sudo apt install vcenter-server=<VERSION_BEFORE_6.5> sudo apt-mark hold vcenter-server

2. No fixed release: DOWNGRADE (RHEL / Amazon Linux / Fedora)

dnf --showduplicates list vcenter-server sudo dnf downgrade vcenter-server-<VERSION_BEFORE_6.5> sudo dnf versionlock add vcenter-server

Downgrade risk

Downgrading can break dependent software and may reopen older bugs. Read the distro advisory first and test on a non-production host.

After downgrade

Restart the service, and keep the package held until a fixed release ships.

Exact fixes by distribution

A distro patch exists: prefer upgrading over downgrading.

Fedora 46 · feh · FIXED · 3.13.1-1.fc46 · FEDORA-2026-3c76a13a4f · source

sudo dnf upgrade --advisory=FEDORA-2026-3c76a13a4f

Fedora ELN · setroubleshoot · FIXED · 3.3.37-7.eln159 · FEDORA-2026-f81b122fe1 · source

sudo dnf upgrade --advisory=FEDORA-2026-f81b122fe1

Public exploits and detection

Public code exists for this CVE. Treat unpatched systems as at risk, and only run PoCs in a lab.

GitHub PoC: Schira4396/VcenterKiller (1482 stars)
GitHub PoC: NS-Sp4ce/CVE-2021-21972 (497 stars)
GitHub PoC: horizon3ai/CVE-2021-21972 (270 stars)
GitHub PoC: B1anda0/CVE-2021-21972
Exploit-DB: VMware vCenter Server 7.0 - Remote Code Execution (RCE) (Unauthenticated)
Exploit-DB: VMware vCenter Server 7.0 - Unauthenticated File Upload
Metasploit: VMware vCenter Server Unauthenticated OVA File Upload RCE
Nuclei scan template: VMware vSphere Client (HTML5) - Remote Code Execution

Verify at the official source NVD · CVE Program · CISA KEV catalog · Report a problem with this page
Scores and fixes here are computed automatically from those and other public sources. Confirm with the vendor advisory before changing production systems.

Quick answers

How do I fix CVE-2021-21972?

cloud foundation: upgrade to 3.10.1.2, 4.2; vcenter server: downgrade or apply the listed mitigation. Exact commands for each OS are on this page.

Is CVE-2021-21972 being exploited?

Yes. CVE-2021-21972 is on the CISA Known Exploited Vulnerabilities list, so treat it as patch-now.

What does CVE-2021-21972 affect?

CVE-2021-21972 affects cloud foundation, vcenter server. Severity is critical (CVSS 9.8). 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 underlyin

How urgent is CVE-2021-21972?

Priority 100/100. Critical severity; EPSS top 1%: very likely to be exploited; Exploited in the wild (CISA KEV); Used in ransomware campaigns; Public exploit reference; CISA SSVC: automatable with total technical impact; Remotely exploitable, no login, no user action

Software pages

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References

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