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CVE-2021-21985

CRITICAL severity · CVSS 9.8 · Server-side request forgery (SSRF) · actively exploited (CISA KEV)
9.8CVSS CRITICAL ● exploited ⚠ ransomware
🔴 Actively exploited in the wild (CISA Known Exploited Vulnerabilities). ⚠ Known use in ransomware campaigns. Added to KEV 2021-11-03. US federal agencies must patch by 2021-11-17.

Summary

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.

Impact & exploitability

Attack vectorNetwork
Attack complexityLow
Privileges requiredNone
User interactionNone
Confidentiality impactHigh
Integrity impactHigh
Availability impactHigh
Exploit probability (EPSS)94%

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

Affected products we track (1)

Recommendation

This vulnerability is being actively exploited in the wild — patch affected products urgently. Open any affected product above for its exact safe version.

Last checked: Wed, 10 Jun 2026 22:18:30 UTC