CVE-2021-21985
CRITICALCISA KEVEPSS 100th pctlDescription
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.
How to fix
TridentStack Control can deploy fixes like this automatically across your Windows, macOS, and Linux fleet. See how it works
Remediation is compiled from vendor and distribution security advisories. Always confirm against the linked source for your exact version and platform.
CVSS v3 Vector
Exploitability
Impact
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Exploit Intelligence
Very high risk: more likely to be exploited than 100% of all known CVEs.
VMware vCenter Server Improper Input Validation Vulnerability
VMware vSphere Client contains an improper input validation vulnerability in the Virtual SAN Health Check plug-in, which is enabled by default in vCenter Server, which allows for remote code execution.
Apply updates per vendor instructions.
Remediation due: 2021-11-17
Associated with ransomware campaigns
References
Related Vulnerabilities
Other CWE-918 (Server-Side Request Forgery (SSRF)) vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2024-21893 | High | 8.2 | 100% | KEV + Ransom | - |
| CVE-2021-40438 | Critical | 9.0 | 100% | KEV + Ransom | Fix |
| CVE-2021-34473 | Critical | 9.1 | 100% | KEV + Ransom | Fix |
| CVE-2021-26855 | Critical | 9.1 | 100% | KEV + Ransom | Fix |
| CVE-2022-41040 | High | 8.8 | 100% | KEV + Ransom | Fix |
| CVE-2021-22986 | Critical | 9.8 | 100% | KEV + Ransom | Fix |
Common questions
How do I fix CVE-2021-21985?
Upgrade cloud foundation to 4.2.1 or later.
Is CVE-2021-21985 being actively exploited?
Yes. CVE-2021-21985 is listed in the CISA Known Exploited Vulnerabilities catalog, which means exploitation has been observed in the wild. CISA has also linked it to known ransomware campaigns. US federal agencies were required to remediate it by 2021-11-17. Treat it as a priority whatever its CVSS score says.
How severe is CVE-2021-21985?
CVE-2021-21985 has a CVSS v3 base score of 9.8, rated critical. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
What does CVE-2021-21985 affect?
Published advisories record a fix for cloud foundation (NVD). Only products with a sourced advisory are listed, so treat this as what we can cite rather than a complete inventory.
Embed a live status badge for CVE-2021-21985
Markdown
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TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.
This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-10-30.