CVE-2021-21972
CriticalExploitedPublic exploitThe vSphere Client (HTML5) contains a remote code execution vulnerability in a vCenter Server plugin.
Published May 27, 2021 · Updated Aug 12, 2026 · Also known as TR-21-0173, TR-21-0200, TR-21-0246, TR-21-0412
Key Facts
Patch immediately- CVE-2021-21972 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting Cloud Foundation (Vmware), Vcenter Server (Vmware).
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Feb 25, 2021 and is known to be used in ransomware campaigns. Public exploit code is available.
- EPSS estimates a 100% probability of exploitation in the next 30 days.
- Fixed versions are available, including Cloud Foundation 3.10.1.2, Cloud Foundation 4.2.
- Brandefense priority: patch immediately, because it is listed as exploited in the wild.
CVSS v3.1
9.8
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (30-day exploit likelihood)
100%
Higher than 99.9% of all scored CVEs
Exploited in the wild
Yes
4 catalog listings, used by ransomware
Public exploit code
Available
Proof-of-concept or weaponized module
Get the full CVE-2021-21972 brief as a PDF
Every affected product and fixed release, exploitation status and a first 24 hours response checklist, emailed within minutes.
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).
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Nov 3, 2021 | Nov 17, 2021 | Known |
| Industry KEV feed | Feb 25, 2021 | Nov 17, 2021 | Known |
| CIRCL KEV | Nov 3, 2021 | Nov 17, 2021 | Known |
| ENISA EUVD | Nov 3, 2021 | n/a | Not reported |
Required action: Apply updates per vendor instructions.
Affected Products
44 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Cloud FoundationVmware | >= 4.x before 4.2 | 3.10.1.2 |
| Vcenter ServerVmware | 6.5, 6.5-a, 6.5-b, 6.5-c, 6.5-d, 6.5-e, 6.5-f, 6.5-update1d | n/a |
Patched Releases
Cloud Foundation
3.10.1.2, 4.2
Timeline
Added to Industry KEV feed
Feb 25, 2021
Publicly disclosed
May 27, 2021
Added to CISA KEV
Nov 3, 2021
Added to CIRCL KEV
Nov 3, 2021
Added to ENISA EUVD
Nov 3, 2021
Last updated
Aug 12, 2026
Weakness Type
- CWE-22 Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')
References
- advisoryhttp://feedproxy.google.com/~r/TheHackersNews/~3/5Bw5yldoufM/critical-rce-vulnerability-found-in.html
- advisoryhttps://borncity.com/win/2021/02/24/vmware-fixt-kritische-rce-schwachstelle-im-vsphere-html5-client/
- advisoryhttps://lifars.com/2021/03/vmware-warns-of-critical-remote-code-execution-vulnerability-in-vsphere-html5-client/
- advisoryhttps://nvd.nist.gov/vuln/detail/CVE-2021-21978
- advisoryhttps://securityaffairs.co/wordpress/115285/security/vmware-view-planner-rce.html?utm_source=rss&utm_medium=rss&utm_campaign=vmware-view-planner-rce
FAQ
Common Questions.
The vSphere Client (HTML5) contains a remote code execution vulnerability in a vCenter Server plugin.
Affected: Cloud Foundation (Vmware) versions >= 4.x before 4.2; Vcenter Server (Vmware) versions 6.5, 6.5-a, 6.5-b, 6.5-c, 6.5-d, 6.5-e, 6.5-f, 6.5-update1d. The full list is in the CVE brief.
It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Feb 25, 2021 and is known to be used in ransomware campaigns.
Yes. It was added on Nov 3, 2021 with a federal remediation due date of Nov 17, 2021.
Public exploit code is available.
Fixed versions are available, including Cloud Foundation 3.10.1.2, Cloud Foundation 4.2.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
Is CVE-2021-21972 Running On Your Attack Surface?
Brandefense maps vulnerabilities like this one to your internet-facing assets and tells you exactly where to patch.
Request A Demo