CVE-2021-21986

The vSphere Client (HTML5) contains a vulnerability in a vSphere authentication mechanism for the Virtual SAN Health Check, Site Recovery, vSphere Lifecycle Manager, and VMware Cloud Director Availability plug-ins. A malicious actor with network access to port 443 on vCenter Server may perform actions allowed by the impacted plug-ins without authentication.

Published: 2021-05-26 Last update: 2024-11-21 Assigner: [email protected] Source: [email protected]
NVD Status：Modified，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-21986 is rated High Risk (68.1/100): CVSS Critical severity, with medium exploitation likelihood (EPSS 1.49%). High exploitation likelihood—assess exposure and prioritize remediation.

Risk is dynamic; we continuously reassess and refresh what is shown on this page as upstream context changes.

Exploit prediction scoring system (EPSS) score for CVE-2021-21986

EPSS lead: Daily EPSS estimates relative likelihood of exploitation; percentile ranks this CVE among scored vulnerabilities (higher = more severe relative rank).

# Date Old EPSS score New EPSS score Delta (New - Old)
1 2026-03-04 0.92% 1.49% +0.57%
2 2026-03-01 1.49% 0.92% -0.57%
3 2026-02-04 — 1.49% —

Full EPSS history (45 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-21986

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
9.8 3.1 CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Click to expand
Attack vector (AV:N)
Could be attacked over the internet or any normal routed network—not just someone sitting at the machine.
Attack complexity (AC:L)
Once they can reach the bug, pulling it off is straightforward—no weird race conditions or rare setup.
Privileges required (PR:N)
No account or special rights needed—anonymous or random user is enough.
User interaction (UI:N)
Nobody has to click “OK” or open a trap file; it can work without a victim helping.
Scope (S:U)
Damage stays in the same “trust bubble” as the broken component—no big spill into unrelated systems.
Confidentiality (C:H)
Serious risk that confidential data gets exposed in a big way.
Integrity (I:H)
They could widely tamper with or forge data—trust in the data is badly hurt.
Availability (A:H)
Could take the service down hard or make it unusable for people who depend on it.
 3.9 5.9 [email protected]
10.0 2.0 HIGH
AV:N/AC:L/Au:N/C:C/I:C/A:C Click to expand
Access vector (AV:N)
Can be exploited remotely over network reachability.
Access complexity (AC:L)
Exploitation conditions are straightforward and predictable.
Authentication (AU:N)
No authentication is required.
Confidentiality impact (C:C)
Complete confidentiality impact.
Integrity impact (I:C)
Complete integrity impact.
Availability impact (A:C)
Complete availability impact.
 10.0 10.0 [email protected]

Weakness enumeration for CVE-2021-21986

Affected software / configurations for CVE-2021-21986

Vendor Product Version Raw CPE
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:-:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:a:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:b:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:c:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:d:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:e:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:f:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:update1:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:update1b:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:update1c:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:update1d:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:update1e:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:update1g:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:update2:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:update2b:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:update2c:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:update2d:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:update2g:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:update3:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:update3d:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:update3f:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:update3k:*:*:*:*:*:*
vmware vcenter_server 6.5 cpe:2.3:a:vmware:vcenter_server:6.5:update3n:*:*:*:*:*:*
vmware vcenter_server 6.7 cpe:2.3:a:vmware:vcenter_server:6.7:-:*:*:*:*:*:*
vmware vcenter_server 6.7 cpe:2.3:a:vmware:vcenter_server:6.7:a:*:*:*:*:*:*
vmware vcenter_server 6.7 cpe:2.3:a:vmware:vcenter_server:6.7:b:*:*:*:*:*:*
vmware vcenter_server 6.7 cpe:2.3:a:vmware:vcenter_server:6.7:d:*:*:*:*:*:*
vmware vcenter_server 6.7 cpe:2.3:a:vmware:vcenter_server:6.7:update1:*:*:*:*:*:*
vmware vcenter_server 6.7 cpe:2.3:a:vmware:vcenter_server:6.7:update1b:*:*:*:*:*:*
vmware vcenter_server 6.7 cpe:2.3:a:vmware:vcenter_server:6.7:update2:*:*:*:*:*:*
vmware vcenter_server 6.7 cpe:2.3:a:vmware:vcenter_server:6.7:update2a:*:*:*:*:*:*
vmware vcenter_server 6.7 cpe:2.3:a:vmware:vcenter_server:6.7:update2c:*:*:*:*:*:*
vmware vcenter_server 6.7 cpe:2.3:a:vmware:vcenter_server:6.7:update3:*:*:*:*:*:*
vmware vcenter_server 6.7 cpe:2.3:a:vmware:vcenter_server:6.7:update3a:*:*:*:*:*:*
vmware vcenter_server 6.7 cpe:2.3:a:vmware:vcenter_server:6.7:update3b:*:*:*:*:*:*
vmware vcenter_server 6.7 cpe:2.3:a:vmware:vcenter_server:6.7:update3f:*:*:*:*:*:*
vmware vcenter_server 6.7 cpe:2.3:a:vmware:vcenter_server:6.7:update3g:*:*:*:*:*:*
vmware vcenter_server 6.7 cpe:2.3:a:vmware:vcenter_server:6.7:update3j:*:*:*:*:*:*
vmware vcenter_server 6.7 cpe:2.3:a:vmware:vcenter_server:6.7:update3l:*:*:*:*:*:*
vmware vcenter_server 6.7 cpe:2.3:a:vmware:vcenter_server:6.7:update3m:*:*:*:*:*:*
vmware vcenter_server 7.0 cpe:2.3:a:vmware:vcenter_server:7.0:-:*:*:*:*:*:*
vmware vcenter_server 7.0 cpe:2.3:a:vmware:vcenter_server:7.0:a:*:*:*:*:*:*
vmware vcenter_server 7.0 cpe:2.3:a:vmware:vcenter_server:7.0:b:*:*:*:*:*:*
vmware vcenter_server 7.0 cpe:2.3:a:vmware:vcenter_server:7.0:c:*:*:*:*:*:*
vmware vcenter_server 7.0 cpe:2.3:a:vmware:vcenter_server:7.0:d:*:*:*:*:*:*
vmware vcenter_server 7.0 cpe:2.3:a:vmware:vcenter_server:7.0:update1:*:*:*:*:*:*
vmware vcenter_server 7.0 cpe:2.3:a:vmware:vcenter_server:7.0:update1a:*:*:*:*:*:*
vmware vcenter_server 7.0 cpe:2.3:a:vmware:vcenter_server:7.0:update1c:*:*:*:*:*:*
vmware vcenter_server 7.0 cpe:2.3:a:vmware:vcenter_server:7.0:update1d:*:*:*:*:*:*
vmware vcenter_server 7.0 cpe:2.3:a:vmware:vcenter_server:7.0:update2:*:*:*:*:*:*
vmware vcenter_server 7.0 cpe:2.3:a:vmware:vcenter_server:7.0:update2a:*:*:*:*:*:*
vmware cloud_foundation >= 3.0, < 3.10.2.1 cpe:2.3:a:vmware:cloud_foundation:*:*:*:*:*:*:*:*
vmware cloud_foundation >= 4.0, < 4.2.1 cpe:2.3:a:vmware:cloud_foundation:*:*:*:*:*:*:*:*

References for CVE-2021-21986

cvelogic Threat Intelligence