# CVE-2021-21985: VMware vCenter Server Improper Input Validation Vulnerability

Source: https://junglewise.ai/threats/cve-2021-21985-vmware-vcenter-server-improper-input-validation-vulnerability  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2021-11-03. Updated: 2026-05-10  
License: CC BY 4.0 with a link back

CVE-2021-21985 · Severity: critical · CVSS 9.8 · Exploited in the wild · Published 2021-11-03

The VMware vSphere Client (HTML5) contains a remote code execution vulnerability due to improper input validation in the Virtual SAN Health Check plug-in. A malicious actor with network access to port 443 can exploit this to execute commands with unrestricted privileges on the underlying operating system hosting vCenter Server.

## Quick answers

**Is CVE-2021-21985 exploited in the wild?** Yes. CVE-2021-21985 is known to be exploited in the wild, first recorded on 3 November 2021. Treat it as urgent.

**How severe is CVE-2021-21985?** Critical severity, with a CVSS score of 9.8, published 3 November 2021.

**Which products and versions are affected?** VMware vCenter Server; VMware vSphere Client (HTML5).

**Is there a fix for CVE-2021-21985?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**How is CVE-2021-21985 attacked?** It is attacked over the network, in a network appliance.

**Am I affected by CVE-2021-21985?** Check whether anything you run is named in the advisory. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- VMware vCenter Server
- VMware vSphere Client (HTML5)

## Timeline

- 2021-11-03: disclosed
- 2021-11-03: kev added: Added to CISA Known Exploited Vulnerabilities Catalog
- 2021-11-17: other: CISA KEV due date for remediation
- 2021-07-13: other: Exploit code published on Packet Storm