CVE-2021-21986

Name: CVE-2021-21986
Creator: NVD / NIST
Published: 2021-05-26T15:15:07.973+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

CRITICALCVSS 9.8/10EPSS 12.92%

Last modified Jun 17, 2026

CVE-2021-21986 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. The vSphere Client (HTML5) contains a vulnerability in a vSphere authentication mechanism for the Virtual SAN Health Check, Site Recovery, vSphere Lifecycle Manager, and VMware Cloud Director Availability plug-ins. A malicious actor with network access to port 443 on vCenter Server may perform actions allowed by the impacted plug-ins without authentication.. EPSS estimates a 12.92% chance of exploitation in the next 30 days.

Description

The vSphere Client (HTML5) contains a vulnerability in a vSphere authentication mechanism for the Virtual SAN Health Check, Site Recovery, vSphere Lifecycle Manager, and VMware Cloud Director Availability plug-ins. A malicious actor with network access to port 443 on vCenter Server may perform actions allowed by the impacted plug-ins without authentication.

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

12.92%

95.8th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-306

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
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
https://www.vmware.com/security/advisories/VMSA-2021-0010.htmlVendor Advisory

Timeline

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

Frequently Asked Questions

What is CVE-2021-21986?

How severe is CVE-2021-21986?

CVE-2021-21986 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 12.92% probability of exploitation in the next 30 days.

How do I fix CVE-2021-21986?

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-2021-21986?

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

Scan your code now

Source: NVD / NIST