Vulnerability Details : CVE-2021-21985

Public exploit exists!
Used for ransomware!
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.
Published 2021-05-26 15:15:08
Updated 2025-04-02 16:53:15
Source VMware
View at NVD,   CVE.org
Vulnerability category: Execute code

Products affected by CVE-2021-21985

CVE-2021-21985 is in the CISA Known Exploited Vulnerabilities Catalog

This issue is known to have been leveraged as part of a ransomware campaign.
CISA vulnerability name:
VMware vCenter Server Improper Input Validation Vulnerability
CISA required action:
Apply updates per vendor instructions.
CISA description:
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.
Notes:
https://nvd.nist.gov/vuln/detail/CVE-2021-21985
Added on 2021-11-03 Action due date 2021-11-17

Exploit prediction scoring system (EPSS) score for CVE-2021-21985

EPSS FAQ
94.37%
Probability of exploitation activity in the next 30 days EPSS Score History
~ 100 %
Percentile, the proportion of vulnerabilities that are scored at or less

Metasploit modules for CVE-2021-21985

  • VMware vCenter Server Virtual SAN Health Check Plugin RCE
    Disclosure Date: 2021-05-25
    First seen: 2021-07-12
    exploit/linux/http/vmware_vcenter_vsan_health_rce
    This module exploits Java unsafe reflection and SSRF in the VMware vCenter Server Virtual SAN Health Check plugin's ProxygenController class to execute code as the vsphere-ui user. See the vendor advisory for affected and patched versions. Tested a

CVSS scores for CVE-2021-21985

Base Score Base Severity CVSS Vector Exploitability Score Impact Score Score Source First Seen
10.0
 HIGH AV:N/AC:L/Au:N/C:C/I:C/A:C
10.0
10.0
 NIST
9.8
 CRITICAL CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.9
5.9
 134c704f-9b21-4f2e-91b3-4a467353bcc0 2025-01-29
9.8
 CRITICAL CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.9
5.9
 NIST

CWE ids for CVE-2021-21985

  • The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.
    Assigned by:
    • 134c704f-9b21-4f2e-91b3-4a467353bcc0 (Secondary)
    • nvd@nist.gov (Primary)
  • The product uses external input with reflection to select which classes or code to use, but it does not sufficiently prevent the input from selecting improper classes or code.
    Assigned by: 134c704f-9b21-4f2e-91b3-4a467353bcc0 (Secondary)
  • The web server receives a URL or similar request from an upstream component and retrieves the contents of this URL, but it does not sufficiently ensure that the request is being sent to the expected destination.
    Assigned by:
    • 134c704f-9b21-4f2e-91b3-4a467353bcc0 (Secondary)
    • nvd@nist.gov (Primary)

References for CVE-2021-21985

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