vmware vcenter-server CVE-2021-21985 vulnerability in VMware Products
Published on May 26, 2021

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 Advisory Vendor Advisory NVD

Known Exploited Vulnerability

This VMware vCenter Server Remote Code Execution Vulnerability is part of CISA's list of Known Exploited Vulnerabilities. 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.

The following remediation steps are recommended / required by November 17, 2021: Apply updates per vendor instructions.

Vulnerability Analysis

CVE-2021-21985 can be exploited with network access, and does not require authorization privileges or user interaction. This vulnerability is considered to have a low attack complexity. It has the highest possible exploitability rating (3.9). The potential impact of an exploit of this vulnerability is considered to be critical as this vulnerability has a high impact to the confidentiality, integrity and availability of this component.

What is a SSRF Vulnerability?

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. By providing URLs to unexpected hosts or ports, attackers can make it appear that the server is sending the request, possibly bypassing access controls such as firewalls that prevent the attackers from accessing the URLs directly. The server can be used as a proxy to conduct port scanning of hosts in internal networks, use other URLs such as that can access documents on the system (using file://), or use other protocols such as gopher:// or tftp://, which may provide greater control over the contents of requests.

CVE-2021-21985 has been classified to as a SSRF vulnerability or weakness.


Products Associated with CVE-2021-21985

You can be notified by stack.watch whenever vulnerabilities like CVE-2021-21985 are published in these products:

VMware Vcenter Server
 
VMware Cloud Foundation
 

What versions are vulnerable to CVE-2021-21985?