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Vulnerabilities

Vulnerability · CVE-2021-21994

SFCB (Small Footprint CIM Broker) as used in ESXi has an authentication bypass vulnerability.

Published Jul 13, 2021 · catalog updated Jun 17, 2026 · cloud foundation

Last checked Nov 7, 2026. A connected source was read within the last 7 days.

Check if you run it

No confirmed exploitation is on record for CVE-2021-21994. EPSS is 1.17%. Act only if a listed version of cloud foundation is installed.

Gaps on this record

  • No vendor fix or required action is stored. Compare the linked advisory before you change production.

Same product and reporting

Severity
Critical9.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
1.17%
Remediation
Version ranges on file
Affected products
cpe vmware/cloud foundation · cpe vmware/esxi

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.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • cpe vmware/cloud foundation< 3.10.2
  • cpe vmware/cloud foundation< 4.3
  • cpe vmware/esxi6.5

How to fix CVE-2021-21994

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2021-21994. EPSS is 1.17%. Act only if a listed version of cloud foundation is installed.

Which versions are affected?

Compare what you have installed with vmware/cloud foundation < 3.10.2; vmware/cloud foundation < 4.3. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

CWE-287: Improper Authentication. EPSS 1.17%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Technology hubs

VMware security

Code

The project this record applies to. Exploit listings stay in References.

No public source repository is identified for this product.

Timeline

Detection, updates, and resolution for this record.

  1. Jul 13, 2021 · Monitored products — critical

    Detected

    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.

  2. Jun 17, 2026 · Monitored products — critical

    Updated

    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.

Sources

  • CVE.orgVulnerability recordCVE-2021-21994

    Official CVE identifier

    cve.org
  • Monitored products — criticalVendor advisoryCVE-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.

    nvd.nist.gov

References

Freshness

Last verified in this catalog Nov 7, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.

  • Monitored products — criticalNov 5, 2026
  • CVE.orgNov 2, 2026