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CVE-2021-21994

30
FAUCET Score

CVE-2021-21994 describes an authentication bypass vulnerability in the SFCB component of VMware ESXi and Cloud Foundation. This critical flaw (CVSS 9.8) allows an unauthenticated attacker with network access to port 5989 to bypass authentication by sending a specially crafted request, leading to full compromise of confidentiality, integrity, and availability. While no public exploit code or active exploitation has been observed, the vulnerability has garnered some community discussion and media coverage, indicating awareness within the security community.

Impacted Technologies

VendorProductVersion(s)CPE
>= 3.0, < 3.10.2CPE matchmatch criteria
cpe:2.3:a:vmware:cloud_foundation:*:*:*:*:*:*:*:*
>= 4.0, < 4.3CPE matchmatch criteria
cpe:2.3:o:vmware:cloud_foundation:*:*:*:*:*:*:*:*
6.5CPE matchmatch criteria
cpe:2.3:o:vmware:esxi:6.5:-:*:*:*:*:*:*
6.5CPE matchmatch criteria
cpe:2.3:o:vmware:esxi:6.5:650-201701001:*:*:*:*:*:*
6.5CPE matchmatch criteria
cpe:2.3:o:vmware:esxi:6.5:650-201703001:*:*:*:*:*:*

CVSS Data

CVSS version used by this source: 3.1

9.8CRITICAL

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

Attack Vector
NETWORK
Attack Complexity
LOW
Privileges Required
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality Impact
HIGH
Integrity Impact
HIGH
Availability Impact
HIGH
Exploitability Score
3.9
Impact Score
5.9
CvssVersion
3.1

Exploit Intelligence

EPSS Score
1.16%
Probability of exploitation in next 30 days
EPSS Percentile
63.8%
Percentile rank of EPSS score among Peer Group
As of 2026-07-28
Model: v2026.06.15
This CVE's current EPSS score of 0.0116 is in the 50th percentile among its peer group of 36,897 CVEs.

Social Chatter

The average CVE in this peer group has 0.0 Twitter, 0.1 Reddit, 0.3 Bluesky, 0.3 Mastodon, and 2.4 GitHub mentions.

Media Mentions

The average CVE in this peer group has 0.3 InfoSec Media, 0.0 Vendor Blog, and 0.0 Security Researcher mentions.

Remediation

Vendor Patches (1)

vmwarevendor investigatingvia nvd_reference
View patch

References

vmware.com / security/advisories/VMSA-2021-0014.html
Vendor Advisory