CVE-2021-21985
VMware vCenter Server Improper Input Validation Vulnerability
IN CISA KEV
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.
- Vendor
- VMware
- Product
- vCenter Server
- CVSS 3.1
- 9.8 (critical), scored by NVD (primary)CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CVSS 3.1
- 9.8 (critical), scored by 134c704f-9b21-4f2e-91b3-4a467353bcc0CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Published
- 2021-05-26
- NVD modified
- 2026-08-12
- NVD status
- Analyzed
CISA KEV
- Date added
- 2021-11-03
- Due date
- 2021-11-17
- Ransomware use
- Known
- Required action
- Apply updates per vendor instructions.
EPSS
100% chance of exploitation in the next 30 days (percentile 99th)
FIRST EPSS, updated 17 Oct 2026. About EPSS
CVSS is severity, EPSS is likelihood, KEV means already exploited. EPSS is a statistical probability, not a certainty: a low score does not make a bug safe, and a high one does not prove it is being exploited.
References
- packetstormsecurity.com (Third Party Advisory, VDB Entry)
- www.vmware.com (Vendor Advisory)
- packetstormsecurity.com (Third Party Advisory, VDB Entry)
- www.vmware.com (Vendor Advisory)
- www.cisa.gov (US Government Resource)
Data last updated 18 Oct 2026. Sources: NVD API 2.0, CISA KEV catalog, FIRST EPSS. Links: NVD, CISA KEV. Metadata only. ThreatWire does not host exploit code.