How severe is CVE-2021-21994?

CVE-2021-21994 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.

Is CVE-2021-21994 being actively exploited?

It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (66th percentile), an estimate of the probability of exploitation in the next 30 days.

What products are affected by CVE-2021-21994?

CVE-2021-21994 primarily affects Vmware Cloud Foundation. In total, 238 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-21994?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.

When was CVE-2021-21994 published?

CVE-2021-21994 was published on 2021-07-13 and last updated on 2026-06-17.

CVE-2021-21994

CVE-2021-21994 is a critical-severity vulnerability in Vmware Cloud Foundation with a CVSS 3.x base score of 9.8. It is not currently listed as actively exploited by CISA, and its EPSS exploit-prediction score is low. The underlying weakness is classified as CWE-287.

Key facts

Severity: Critical (CVSS 3.x base score 9.8)
CVSS v2: 6.8
EPSS exploit prediction: 1% (66th percentile)
Actively exploited: Not listed in CISA KEV
Weakness: CWE-287
Affected product: Vmware Cloud Foundation
Published: 2021-07-13
Last modified: 2026-06-17

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.

Frequently asked questions

What is CVE-2021-21994?: 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.
How severe is CVE-2021-21994?: CVE-2021-21994 has a CVSS 3.x base score of 9.8, rated critical severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is high, integrity high, and availability high.
Is CVE-2021-21994 being actively exploited?: It is not currently listed in CISA's KEV catalog. Its EPSS exploit-prediction score is 1% (66th percentile), an estimate of the probability of exploitation in the next 30 days.
What products are affected by CVE-2021-21994?: CVE-2021-21994 primarily affects Vmware Cloud Foundation. In total, 238 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-21994?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Given its critical severity, prioritise patching exposed systems.
When was CVE-2021-21994 published?: CVE-2021-21994 was published on 2021-07-13 and last updated on 2026-06-17.

References

https://www.vmware.com/security/advisories/VMSA-2021-0014.html

Affected products (238)

cpe:2.3:a:vmware:cloud_foundation:*:*:*:*:*:*:*:*
cpe:2.3:o:vmware:cloud_foundation:*:*:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:-:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201701001:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201703001:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201703002:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201704001:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707101:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707102:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707103:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707201:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707202:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707203:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707204:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707205:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707206:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707207:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707208:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707209:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707210:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707211:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707212:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707213:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707214:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707215:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707216:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707217:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707218:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707219:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707220:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201707221:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201710001:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201712001:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201803001:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201806001:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201808001:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201810001:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201810002:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201811001:*:*:*:*:*:*
cpe:2.3:o:vmware:esxi:6.5:650-201811002:*:*:*:*:*:*

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