Is CVE-2021-21973 in the CISA KEV catalog?

Yes. CVE-2021-21973 is on the CISA Known Exploited Vulnerabilities list, added 2022-03-07.

What is the CVSS severity of CVE-2021-21973?

CVE-2021-21973 has a CVSS v3 base score of 5.3 (MEDIUM).

What is the EPSS score for CVE-2021-21973?

CVE-2021-21973 has an EPSS score of 88.01% (100th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-21973?

Upgrade cloud foundation to 4.2 or later.

CVE & CISA-KEV Catalog

CVE-2021-21973

MEDIUMCISA KEVEPSS 100th pctl

5.3

CVSS v3

NVD

Description

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).

CWE-918Server-Side Request Forgery (SSRF)

How to fix

Remediation Available

cloud foundationNVD

Affected:>= 4.0, < 4.2Fixed in:4.2CVE-2021-21973derived from NVD

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

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityNone

AvailabilityNone

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N

Exploit Intelligence

88.01%probability of exploitation in 30 days

100thpercentile

Very high risk: more likely to be exploited than 100% of all known CVEs.

Known Exploited Vulnerability (CISA KEV)

VMware vCenter Server and Cloud Foundation Server Side Request Forgery (SSRF) Vulnerability

VMware vCenter Server and Cloud Foundation Server contain a SSRF vulnerability due to improper validation of URLs in a vCenter Server plugin. This allows for information disclosure.

Apply updates per vendor instructions.

Remediation due: 2022-03-21

References

Vendor Advisory1

vmware.com

Government Resource1

cisa.gov

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	Fix
CVE-2021-34473	Critical	9.1	100%	KEV + Ransom	Fix
CVE-2021-26855	Critical	9.1	100%	KEV + Ransom	Fix
CVE-2021-21985	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2022-41040	High	8.8	100%	KEV + Ransom	Fix

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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.