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ExploitedIn CISA KEVFix available

CVE-2021-21985

Exploitation confirmed. First attested on 2021-11-03 by CISA-ADP, CISA KEV, GCVE · kevintel, GCVE · shadowserver.

  • Published2021-05-26
  • WeaknessCWE-20 · CWE-470 · CWE-918

Am I affected?

With a domain, we read the version its public headers and pages expose. A distribution build can carry the fix under an older number.

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.

Timeline

dates in UTC
  1. 2021-05-2615:15CVE publishedNVD
  2. 2021-11-03Added to the CISA KEV catalogCISA KEV
  3. 2021-11-03Listed as exploited by GCVEGCVE
  4. 2021-11-03Exploitation first reportedCISA KEV
  5. 2025-01-2917:56SSVC exploitation set to activeCISA-ADP

Observed activity

isMalicious corpus · updated 2026-11-03 21:37 UTC
Indicators tagged with this CVE, per day0 indicators over 7 days
Block these indicators
  • Firewall list (EDL, text): https://api.ismalicious.com/edl/cve/CVE-2021-21985?format=txt
  • CSV export: https://api.ismalicious.com/edl/cve/CVE-2021-21985?format=csv
  • TAXII collection of exploited CVEs
  • The EDL and CSV take an API key on the Pro plan.

Versions per branch

NVD
Vmware vcenter server
BranchAffectedFixed in
6.5= 6.5no fix published
6.7= 6.7no fix published
7.0= 7.0no fix published
Vmware cloud foundation
BranchAffectedFixed in
4.x≥ 4.0, < 4.2.14.2.1
3.x≥ 3.0, < 3.10.2.13.10.2.1

as publishedRanges as NVD and OSV publish them; a distribution’s build can be fixed under an older number.

Products declared by the CNA1 product

As vmware, the CNA that assigned this CVE, declared them in the CVE record; versions as written.

  • VMware vCenter Server and VMware Cloud Foundation
    Affected
    • = 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)no fix stated

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2021-07-13

Fix

  1. CISA’s required action: Apply updates per vendor instructions.due 2021-11-17

Advisories and patches

Detection

read 2026-11-02 22:42 UTC
Nuclei template
available
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof-of-concept repositories
10 repositories, unverifiedbigbroke/CVE-2021-21985alt3kx/CVE-2021-21985_PoConSec-fr/CVE-2021-21985-Checkermauricelambert/CVE-2021-21985xnianq/cve-2021-21985_exp
PoC-in-GitHub
Metasploit modules
1 moduleexploit/linux/http/vmware_vcenter_vsan_health_rcerank: excellentModule metadata: Metasploit Framework, © Rapid7, Inc., BSD-3-Clause.
Metasploit Framework

CISA Known Exploited Vulnerability

Date Added
2021-11-03
Patch Due Date
2021-11-17
Ransomware Use
Known
Required Action
Apply updates per vendor instructions.

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2021-05-26
Last Modified
2026-08-12
NVD status
Analyzed
GitHub Advisory
GHSA-rg6m-2r9v-c5fj

Frequently asked questions

What is CVE-2021-21985?

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.

Is CVE-2021-21985 actively exploited?

Yes. CVE-2021-21985 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, meaning it has been confirmed as actively exploited in the wild. CISA requires federal agencies to patch by 2021-11-17.

What is the CVSS score for CVE-2021-21985?

CVE-2021-21985 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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Sources for this record