CVE-2021-21985
CriticalExploitedPublic exploitThe vSphere Client (HTML5) contains a remote code execution vulnerability due to lack of input validation in the Virtual SAN Health Check plug-in which is enabled by default in vCenter Server.
Published Jun 7, 2021 · Updated Aug 12, 2026 · Also known as TR-21-0402
Key Facts
Patch immediately- CVE-2021-21985 is a critical-severity vulnerability (CVSS 9.8 v3.1) affecting Cloud Foundation (Vmware), Vcenter Server (Vmware), VMware vCenter Server and VMware Cloud Foundation.
- It is exploited in the wild, listed in CISA KEV, Industry KEV feed, CIRCL KEV, ENISA EUVD since Jun 4, 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 3.10.2.1, Cloud Foundation 4.2.1.
- 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-2021-21985 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 due to lack of input validation in the Virtual SAN Health Check plug-in which is enabled by default in vCenter Server. 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.
Known-Exploited Catalog Listings
| Catalog | Added | Remediation due | Ransomware use |
|---|---|---|---|
| CISA KEV | Nov 3, 2021 | Nov 17, 2021 | Known |
| Industry KEV feed | Jun 4, 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
53 affected entries in total| Product | Affected versions | Fixed in |
|---|---|---|
| Cloud FoundationVmware | See advisory | 3.10.2.1 |
| Vcenter ServerVmware | 6.5, 6.5-a, 6.5-b, 6.5-c, 6.5-d, 6.5-e, 6.5-f, 6.5-update1 | n/a |
| VMware vCenter Server and VMware Cloud Foundation | >= VMware vCenter Server (7.x before 7.0 U2b, 6.7 before 6.7 U3n, 6.5 before 6.5 U3p) and VMware Cloud Foundation (4.x before 4.2.1, 3.x before 3.10.2.1) | n/a |
Patched Releases
Cloud Foundation
3.10.2.1, 4.2.1
Timeline
Added to Industry KEV feed
Jun 4, 2021
Publicly disclosed
Jun 7, 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-20 Improper Input Validation
- CWE-470 Use of Externally-Controlled Input to Select Classes or Code ('Unsafe Reflection')
- CWE-918 Server-Side Request Forgery (SSRF)
References
- advisoryhttp://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-14779
- advisoryhttp://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-14782
- advisoryhttp://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-14803
- advisoryhttp://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2020-27221
- advisoryhttp://feedproxy.google.com/~r/TheHackersNews/~3/5Bw5yldoufM/critical-rce-vulnerability-found-in.html
FAQ
Common Questions.
The vSphere Client (HTML5) contains a remote code execution vulnerability due to lack of input validation in the Virtual SAN Health Check plug-in which is enabled by default in vCenter Server.
Affected: Cloud Foundation (Vmware); 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-update1; VMware vCenter Server and VMware Cloud Foundation versions >= VMware vCenter Server (7.x before 7.0 U2b, 6.7 before 6.7 U3n, 6.5 before 6.5 U3p) and VMware Cloud Foundation (4.x before 4.2.1, 3.x before 3.10.2.1). 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 Jun 4, 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 3.10.2.1, Cloud Foundation 4.2.1.
Brandefense priority: patch immediately, because it is listed as exploited in the wild.
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