CVE-2021-21973: listed in the CISA KEV catalog

CVE-2021-21973 · CVSS 5.3 MEDIUM · EPSS 88% · KEV 2022-03-07

The vSphere Client (HTML5) contains an SSRF (Server Side Request Forgery) vulnerability due to improper validation of URLs in a vCenter Server plugin. A malicious actor with network access to port 443 may exploit this issue by sending a POST request to vCenter Server plugin leading to information disclosure. 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).

Is CVE-2021-21973 exploited?

• Listed in the CISA KEV catalog on 2022-03-07.
• Federal remediation due 2022-03-21.
• Past that date by 1608 days.
• EPSS puts exploitation in the next 30 days at 88%.
• Public exploit code: none found in monitored sources.
• Public detection rules exist.

Which products and versions are affected?

No affected package list recorded here yet.

Is there a patch?

No patch identifier recorded here yet.

What PlainSec published about CVE-2021-21973

• Node Kernel Bugs on GKE COS Nodes Enable Host Escalation (2026-04-15)
• Google Cloud Issues Multiple Linux Kernel Privilege Escalation Fixes for GKE Nodes (2026-04-07)
• Multiple Linux Kernel Flaws Elevate Privileges on GCP Container Nodes (2026-04-03)
• Multiple High-Severity Cloud Vulnerabilities Impact Container Nodes (2026-04-01)

Primary sources

• NVD record
• CISA KEV catalog
• Nuclei template

What this record does not say

• No affected package data.
• No patch identifier.

KEV and EPSS are re-checked daily. Record last updated 2026-08-15.