Is CVE-2021-21994 in the CISA KEV catalog?

No. CVE-2021-21994 is not currently on the CISA Known Exploited Vulnerabilities list.

What is the CVSS severity of CVE-2021-21994?

CVE-2021-21994 has a CVSS v3 base score of 9.8 (CRITICAL).

What is the EPSS score for CVE-2021-21994?

CVE-2021-21994 has an EPSS score of 1.16% (63th percentile), estimating the probability of exploitation in the next 30 days.

How do I fix CVE-2021-21994?

Upgrade cloud foundation to 3.10.2 or later.

CVE & CISA-KEV Catalog

CVE-2021-21994

CRITICAL

9.8

CVSS v3

NVD

Description

SFCB (Small Footprint CIM Broker) as used in ESXi has an authentication bypass vulnerability. A malicious actor with network access to port 5989 on ESXi may exploit this issue to bypass SFCB authentication by sending a specially crafted request.

CWE-287Improper Authentication

How to fix

Remediation Available

cloud foundationNVD

Affected:>= 3.0, < 3.10.2Fixed in:3.10.2CVE-2021-21994derived from NVD

Affected:>= 4.0, < 4.3Fixed in:4.3CVE-2021-21994derived from NVD

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

ConfidentialityHigh

IntegrityHigh

AvailabilityHigh

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

Exploit Intelligence

1.16%probability of exploitation in 30 days

63rdpercentile

Moderate risk: more likely to be exploited than 63% of all known CVEs.

References

Vendor Advisory1

vmware.com

Related Vulnerabilities

Other CWE-287 (Improper Authentication) vulnerabilities, ordered by exploit likelihood. View all

CVE	Severity	CVSS	EPSS	Exploited	Fix
CVE-2023-35082	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2023-35078	Critical	9.8	100%	KEV + Ransom	Fix
CVE-2017-7921	Critical	9.8	100%	KEV	-
CVE-2024-7593	Critical	9.8	100%	KEV	-
CVE-2023-46805	High	8.2	100%	KEV + Ransom	-
CVE-2022-40684	Critical	9.8	100%	KEV + Ransom	Fix

Embed a live status badge for CVE-2021-21994

Markdown

[![CVE-2021-21994](https://tridentstack.com/cve/badge/CVE-2021-21994.svg)](https://tridentstack.com/cve/CVE-2021-21994)

HTML

<a href="https://tridentstack.com/cve/CVE-2021-21994"><img src="https://tridentstack.com/cve/badge/CVE-2021-21994.svg" alt="CVE-2021-21994"></a>

Find and fix vulnerabilities across your fleet

TridentStack Control continuously scans your Windows, macOS, and Linux fleet for known vulnerabilities, prioritizes them by severity and active exploitation, and patches them automatically.

Start free

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 2025-10-31.