CVE-2021-21973

Exp

The vSphere Client (HTML5) contains an SSRF (Server Side Request Forgery) vulnerability due to improper validation of URLs in a vCenter Server plugin. A malicious actor with network access to port 443 may exploit this issue by sending a POST request to vCenter Server plugin leading to information disclosure. This affects: VMware vCenter Server (7.x before 7.0 U1c, 6.7 before 6.7 U3l and 6.5 before 6.5 U3n) and VMware Cloud Foundation (4.x before 4.2 and 3.x before 3.10.1.2).

Published: 2021-02-24 Last update: 2025-10-30 Assigner: [email protected] Source: [email protected]
NVD Status：Analyzed，CVE State: published
View at NVD, CVE.org, EUVD

CVE-2021-21973 is rated Critical Active Threat (81.4/100): CVSS Medium severity, with high exploitation likelihood (EPSS 90.39%, 100th percentile). CISA KEV confirms active exploitation (added 2022-03-07) affecting VMware / vCenter Server and Cloud Foundation. a weakness (CWE-918) Unauthenticated remote administrative access may be possible. The CISA remediation deadline has passed—treat as an emergency patch priority.

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

CISA KEV Record for CVE-2021-21973

Name: VMware vCenter Server and Cloud Foundation Server Side Request Forgery (SSRF) Vulnerability · CISA KEV detail

Exploit added: 2022-03-07

Action due: 2022-03-21

Required action: Apply updates per vendor instructions.

Exploit prediction scoring system (EPSS) score for CVE-2021-21973

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 2026-04-27 90.08% 90.39% +0.31%
2 2026-04-20 90.34% 90.08% -0.26%
3 2026-03-04 — 90.34% —

Full EPSS history (79 records total)

Common vulnerability scoring system (CVSS) metrics for CVE-2021-21973

CVSS metrics for this CVE.

Base score Version Severity Vector Exploitability Impact Score source
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N 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:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 1.4 [email protected]
5.3 3.1 MEDIUM
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N 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:L)
Some sensitive info could get out, but not a total data dump.
Integrity (I:N)
Data isn’t meaningfully altered or forged.
Availability (A:N)
Service keeps running; no real outage angle.
 3.9 1.4 134c704f-9b21-4f2e-91b3-4a467353bcc0
5.0 2.0 MEDIUM
AV:N/AC:L/Au:N/C:P/I:N/A:N 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:P)
Partial confidentiality impact.
Integrity impact (I:N)
No integrity impact.
Availability impact (A:N)
No availability impact.
 10.0 2.9 [email protected]

Weakness enumeration for CVE-2021-21973

Affected software / configurations for CVE-2021-21973

Vendor Product Version Raw CPE
vmware cloud_foundation >= 3.0, < 3.10.1.2 cpe:2.3:a:vmware:cloud_foundation:*:*:*:*:*:*:*:*
vmware cloud_foundation >= 4.0, < 4.2 cpe:2.3:a:vmware:cloud_foundation:*:*:*:*:*:*:*:*
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: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 6.7 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 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:*:*:*:*:*:*

References for CVE-2021-21973

cvelogic Threat Intelligence