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Fencer Vulns
critical 9.8

CVE-2021-21972 kev+ ransomware in the critical feed json

The vSphere Client (HTML5) contains a remote code execution vulnerability in a vCenter Server plugin.

published 2021-02-24 5 y ago modified 2026-08-12 2 mo ago also EUVD-2021-9143

cvss
9.8
version 3.1, CNA
cisa kev
Exploited
added 2021-11-03, used in ransomware
epss
99.9%
EPSS 99.9% chance of exploitation in 30 days, percentile 99.9%
public exploits
3
Metasploit, Exploit-DB, plus a Nuclei check

Summary

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).

Patch / fix

cisa required action Apply updates per vendor instructions.

  • vmware cloud_foundation 3.10.1.2, 4.2

Timeline

  1. CISA SSVC: exploitation active
  2. First public exploit (Metasploit exploit/multi/http/vmware_vcenter_uploadova_rce)
  3. Published
  4. Added to CISA KEV
  5. CISA patch deadline

Known exploited

Added
5 y ago
Patch by
2021-11-17 (4 y ago)
Ransomware
Known to be used in ransomware campaigns
Required action
Apply updates per vendor instructions.
Vendor, product
VMware, vCenter Server
CISA name
VMware vCenter Server Remote Code Execution Vulnerability

Ransomware

Groups reported to have exploited it in intrusions.

  • BlackCat ransomware gang
  • Akira ransomware gang

reported by crowdstrike.comblog.qualys.com

Ransomware Vulnerability Matrix by BushidoUK (github.com/BushidoUK/Ransomware-Vulnerability-Matrix), reformatted per CVE. CC BY 4.0

ATT&CK techniques

How it is exploited and what it leads to, in MITRE ATT&CK terms.

  • T1190 Exploit Public-Facing Application exploitation
  • T1059 Command and Scripting Interpreter primary impact

kev release 2025-07-28, att&ck v16.1. KEV to ATT&CK mappings by the MITRE Center for Threat-Informed Defense (Mappings Explorer, Apache-2.0). © 2026 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation. Terms of use

CISA SSVC

Exploitation
Active, exploited in the wild
Automatable
yes
Technical impact
total
Assessed
5 y ago

Exploit prediction

99.87% chance of exploitation in the next 30 days, higher than 99.9% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • Metasploit exploit/multi/http/vmware_vcenter_uploadova_rce VMware vCenter Server Unauthenticated OVA File Upload RCE metasploit exploit, manual rank, 2021-02-23
  • EDB-50056 VMware vCenter Server 7.0 - Remote Code Execution (RCE) (Unauthenticated) webapps, 2021-06-24
  • EDB-49602 VMware vCenter Server 7.0 - Unauthenticated File Upload webapps, 2021-03-01
  • Nuclei template VMware vSphere Client (HTML5) - Remote Code Execution nuclei detection template
  • packetstormsecurity.com http://packetstormsecurity.com/files/161590/VMware-vCenter-Server-7.0-Arbitrary-File-Upload.html referenced PoC, tagged "exploit" by a source, unverified
  • packetstormsecurity.com http://packetstormsecurity.com/files/161695/VMware-vCenter-Server-File-Upload-Remote-Code-Execution.html referenced PoC, tagged "exploit" by a source, unverified
  • packetstormsecurity.com http://packetstormsecurity.com/files/163268/VMware-vCenter-6.5-6.7-7.0-Remote-Code-Execution.html referenced PoC, tagged "exploit" by a source, unverified

CVSS scores

assigned by version score vector
CISA ADP 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
NVD 2.0 10.0 AV:N/AC:L/Au:N/C:C/I:C/A:C

Affected products

  • n/a VMware vCenter Server
  • n/a VMware Cloud Foundation

Classification

Weakness
  • CWE-22 Improper Limitation of a Pathname to a Restricted Directory
Technology feeds

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.