CVE-2021-21985

Name: CVE-2021-21985
Creator: NVD / NIST
Published: 2021-05-26T15:15:07.937+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10Actively ExploitedEPSS 100.00%

Last modified Jun 17, 2026

CVE-2021-21985 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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.. CISA has confirmed active exploitation in the wild. EPSS estimates a 100.00% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

9.8/10

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

EPSS Probability

100.00%

100.0th percentile

Probability of exploitation in the next 30 days. Learn more

Exploitation Status

This vulnerability is listed in CISA’s Known Exploited Vulnerabilities catalog, confirming active exploitation in the wild. Federal agencies must remediate by Nov 17, 2021.

Weakness Enumeration

Affected Software

Vendor	Product	Versions
Vmware	Vcenter Server	6.5
Vmware	Vcenter Server	6.7
Vmware	Vcenter Server	7.0
Vmware	Cloud Foundation	>= 3.0, < 3.10.2.1
Vmware	Cloud Foundation	>= 4.0, < 4.2.1

References

http://packetstormsecurity.com/files/162812/VMware-Security-Advisory-2021-0010.htmlThird Party Advisory, VDB Entry
http://packetstormsecurity.com/files/163487/VMware-vCenter-Server-Virtual-SAN-Health-Check-Remote-Code-Execution.htmlExploit, Third Party Advisory, VDB Entry
https://www.vmware.com/security/advisories/VMSA-2021-0010.htmlVendor Advisory
http://packetstormsecurity.com/files/162812/VMware-Security-Advisory-2021-0010.htmlThird Party Advisory, VDB Entry
http://packetstormsecurity.com/files/163487/VMware-vCenter-Server-Virtual-SAN-Health-Check-Remote-Code-Execution.htmlExploit, Third Party Advisory, VDB Entry
https://www.vmware.com/security/advisories/VMSA-2021-0010.htmlVendor Advisory
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-21985US Government Resource

Timeline

Published: May 26, 2021
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2021-21985?

How severe is CVE-2021-21985?

CVE-2021-21985 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 100.00% probability of exploitation in the next 30 days. This vulnerability is listed in CISA's Known Exploited Vulnerabilities catalog.

How do I fix CVE-2021-21985?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2021-21985?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST