CVE-2021-21986

Severity: critical (CVSS 9.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 13.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2021-05-26 · updated 2026-06-17
Weakness: CWE-306

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.

Affected products

VMware Cloud Foundation: from 3.0 before 3.10.2.1; from 4.0 before 4.2.1 — fixed in 3.10.2.1, 4.2.1
VMware vCenter Server: 6.5, 6.5-a, 6.5-b, 6.5-c, 6.5-d, 6.5-e (+45)
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)

How to fix

Upgrade to a fixed version: VMware Cloud Foundation 3.10.2.1, 4.2.1. Check the vendor advisory for mitigations.

References

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