CVE-2021-21985
n/a VMware vCenter Server and VMware Cloud Foundation
Summary
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…
Published: 2021-05-26
Analysis
🟠 High — imminent exploitation
Weakness: Server-Side Request Forgery (SSRF) (CWE-918). Forces the server to make requests to internal targets.
How it's exploited: Exploitable over the network (internet-reachable), unauthenticated, no user interaction, and with low complexity.
⚠️ Critical combo: remote, unauthenticated and no interaction → trivial to automate.
Impact: Full compromise (confidentiality, integrity and availability).
Status: Exploit probability (EPSS, 30 days): 100% — high.
- Apply the vendor patch according to risk priority.
- Reduce exposure: keep it off the internet; firewall, VPN or network segmentation.
- Detect: turn this CVE into detection rules.
MITRE ATT&CK technique: T1190 · Exploit Public-Facing Application
Practice it in the arsenal: WAF Bypass
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
The vector encodes how it's exploited (translated above, in the analysis). Break it down in the CVSS tool →
Sources: CISA KEV · EPSS · FIRST.org · NVD. Analysis derived from the CVSS vector and exploitation status (no AI). Informational; always verify against the vendor's official advisory.