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CVE-2021-21986

36
FAUCET Score

CVE-2021-21986 is a critical authentication bypass vulnerability in the vSphere Client (HTML5) affecting VMware vCenter Server and Cloud Foundation. An unauthenticated attacker with network access to port 443 can exploit this flaw to perform actions allowed by several vSphere plug-ins, including vSAN Health Check and Site Recovery. With a CVSS score of 9.8, this vulnerability poses a high risk of complete compromise (confidentiality, integrity, availability) due to its network-based attack vector and low attack complexity. While not currently listed on the KEV catalog, the vulnerability has garnered significant community attention and media coverage, with VMware urging immediate patching, though no public exploit code is currently available.

Impacted Technologies

VendorProductVersion(s)CPE
6.5CPE matchmatch criteria
cpe:2.3:a:vmware:vcenter_server:6.5:-:*:*:*:*:*:*
6.5CPE matchmatch criteria
cpe:2.3:a:vmware:vcenter_server:6.5:a:*:*:*:*:*:*
6.5CPE matchmatch criteria
cpe:2.3:a:vmware:vcenter_server:6.5:b:*:*:*:*:*:*
6.5CPE matchmatch criteria
cpe:2.3:a:vmware:vcenter_server:6.5:c:*:*:*:*:*:*
6.5CPE matchmatch criteria
cpe:2.3:a:vmware:vcenter_server:6.5:d:*:*:*:*:*:*

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
12.92%
Probability of exploitation in next 30 days
EPSS Percentile
95.9%
Percentile rank of EPSS score among Peer Group
As of 2026-07-27
Model: v2026.06.15
This CVE's current EPSS score of 0.1292 is in the 92nd 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

Patch Available

Vendor Patches (3)

boschpatch availablevia llm_extracted
View patch
mongodbpatch availablevia llm_extracted
View patch
vmwarevendor investigatingvia nvd_reference
View patch

Vendor Advisories (2)

boschllm-bosch-7104d11cffadb807CRITICAL

VMware vSphere Client RCE and authentication bypass (VMSA-2021-0010)

mongodbllm-mongodb-d2189aa8354d41c5CRITICAL

Multiple VMware vSphere Client vulnerabilities (VMSA-2021-0010)

References

packetstormsecurity.com / files/162812/VMware-Security-Advisory-2021-0010.html
Third Party AdvisoryVDB Entry
vmware.com / security/advisories/VMSA-2021-0010.html
Vendor Advisory