CVE-2021-21985

Confirmed PUBLISHED

The vSphere Client (HTML5) contains a remote code execution vulnerability due to lack of input validation in the Virtual SAN Health Check plug-in...

VMware · VMware vCenter Server and VMware Cloud Foundation

Exploited in the wild Used in malware PoC available

Recommended Action

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.

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Confidence

Confirmed

Exploitation Status

Exploited in the wild

Observed in Sensors

Attempts (30d)

—

Unique Attacker IPs

—

CISA KEV

In CISA KEV

CVSS / EPSS

9.8 Critical EPSS 100.0%

At a Glance

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.

malware cisa nuclei_scanner ransomware metasploit

CVE Published: May 26, 2021
Exploitation Reported: Nov 03, 2021
CVSS: 9.8 Critical
EPSS: 100.0%

Remote Low complexity No user interaction Unauthenticated

Affected Versions

Vendor	Product	Version	Status
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)	Affected

CVE References

vmware.com/security/advisories/VMSA-2021-0010.html vmware.com · CVE Record https://www.vmware.com/security/advisories/VMSA-2021-0010.html
packetstormsecurity.com/files/162812/VMware-Security-Advisory-2021-0... packetstormsecurity.com · CVE Record http://packetstormsecurity.com/files/162812/VMware-Security-Advisory-...
packetstormsecurity.com/files/163487/VMware-vCenter-Server-Virtual-S... packetstormsecurity.com · CVE Record http://packetstormsecurity.com/files/163487/VMware-vCenter-Server-Vir...

Recommended Actions

Prioritize remediation. Validate affected assets and apply vendor fixes on an accelerated timeline.
Check enrichment artifacts for scanner coverage and available PoCs before rolling remediation validation.
Use the Pro API to automate enrichment, telemetry, and workflow delivery for VM, SOC, and CTI pipelines.

Known Exploited Vulnerability Sources

Catalogues that list this CVE as a known exploited vulnerability.

Per-source evidence links for KEV attestations are available through the KEVIntel Pro API.

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Source	Added
CISA First	2021-11-03 00:00 UTC
The Shadowserver	2026-06-14 00:00 UTC

Scanner Artifacts

Nuclei and Metasploit references linked to this CVE.

Scanner	Reference	Detected
Nuclei	https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-21985.yaml	Apr 25, 2025
Metasploit	https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/linux/http/vmware_vcenter_vsan_health_rce.rb	Apr 28, 2025

CVSS Scores

CVSS v3.1 9.8 Critical

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v2.0 10.0 High

AV:N/AC:L/Au:N/C:C/I:C/A:C

Exploitation Status

Exploited in the wild

Recorded 2021-11-03 00:00:00 UTC · CISA

Used in malware

Recorded 2021-11-03 00:00:00 UTC · CISA

Proof of concept available

Recorded 2021-05-29 13:07:14 UTC · GitHub

Weaknesses (CWE)

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)

Scanner Integrations

Scanner	Reference	Detected
Metasploit	https://github.com/rapid7/metasploit-framework/blob/master/modules/exploits/linux/http/vmware_vcenter_vsan_health_rce.rb	Apr 28, 2025
Nuclei	https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2021/CVE-2021-21985.yaml	Apr 25, 2025

Potential Proof of Concepts

These PoCs are unverified and could contain malware. Use at your own risk.

sknux/CVE-2021-21985_PoC

github · Created 2021-11-09 19:06:29 UTC · 3 stars

VMWARE VCENTER SERVER VIRTUAL SAN HEALTH CHECK PLUG-IN RCE (CVE-2021-21985)

testanull/Project_CVE-2021-21985_PoC

github · Created 2021-06-05 11:03:13 UTC · 31 stars

daedalus/CVE-2021-21985

github · Created 2021-06-04 01:15:14 UTC · 2 stars

CVE-2021-21985 vmware 6.7-9.8 RCE

onSec-fr/CVE-2021-21985-Checker

github · Created 2021-06-01 08:31:05 UTC · 2 stars

CVE-2021-21985 Checker.

alt3kx/CVE-2021-21985_PoC

github · Created 2021-05-29 13:07:14 UTC · 214 stars

VMware vSphere Client (HTML5) - Remote Code Execution

nuclei · Created Unknown

vmware_vcenter_vsan_health_rce

metasploit · Created Unknown

Metasploit module for CVE-2021-21985

Timeline

Key exploitation, disclosure, scanner coverage, and KEV attestation events for this CVE.

14 Jun 2026 00:00 UTC about 1 month ago

14 Jun 2026 00:00 UTC · about 1 month ago

KEV confirmed by The Shadowserver

Exploitation attested by an external source
28 Apr 2025 15:02 UTC about 1 year ago

28 Apr 2025 15:02 UTC · about 1 year ago

Metasploit module available

Exploit module available
25 Apr 2025 00:00 UTC about 1 year ago

25 Apr 2025 00:00 UTC · about 1 year ago

Nuclei template available

Scanner coverage available
3 Nov 2021 00:00 UTC over 4 years ago

3 Nov 2021 00:00 UTC · over 4 years ago

Added to CISA KEV

Listed in the CISA Known Exploited Vulnerabilities catalog
3 Nov 2021 00:00 UTC over 4 years ago

3 Nov 2021 00:00 UTC · over 4 years ago

First public exploitation report

Exploit observed in malware
29 May 2021 13:07 UTC about 5 years ago

29 May 2021 13:07 UTC · about 5 years ago

Public PoC available

Public proof-of-concept code published
26 May 2021 14:04 UTC about 5 years ago

26 May 2021 14:04 UTC · about 5 years ago

CVE published

Vulnerability disclosed publicly
4 Jan 2021 00:00 UTC over 5 years ago

4 Jan 2021 00:00 UTC · over 5 years ago

CVE ID reserved

Identifier reserved by the CNA

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Confidence scoring, exploit status, sensor telemetry, PoCs, scanner integrations, mentions, and tags are available programmatically for VM, SOC, and CTI workflows.

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Pro API Example

GET /api/v2/pro/kevs/CVE-2021-21985

{
  "cve_id": "CVE-2021-21985",
  "title": "The vSphere Client (HTML5) contains a remote code execution vulnerability due...",
  "affected_vendor": "VMware",
  "affected_product": "VMware vCenter Server and VMware Cloud Foundation",
  "affected_versions": [
    { "vendor": "...", "product": "...", "status": "affected", "display_label": "..." }
  ],
  "confidence": "Confirmed",
  "cvss_score": 9.8,
  "epss_score": 0.99999,
  "exploit_status": {
    "exploited_in_the_wild": true,
    "active_exploitation_observed": false
  },
  "sensor_telemetry": { "...": "Pro API fields" },
  "proof_of_concepts": [ "..." ],
  "scanner_integrations": [ "..." ]
}

The free JSON API returns basic KEV fields only. Confidence, telemetry, and artifact enrichment require Pro API access.

CVE-2021-21985

At a Glance

Affected Versions

CVE References

Recommended Actions

Known Exploited Vulnerability Sources

Scanner Artifacts

Virtual Patch

CVSS Scores

Exploitation Status

Weaknesses (CWE)

Scanner Integrations

Potential Proof of Concepts

Timeline

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