How severe is CVE-2021-21973?

CVE-2021-21973 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.

Is CVE-2021-21973 being actively exploited?

Yes. CVE-2021-21973 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2022-03-07, which means active exploitation has been confirmed. It should be prioritised for remediation.

What products are affected by CVE-2021-21973?

CVE-2021-21973 primarily affects Vmware Cloud Foundation. In total, 42 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.

How do I fix CVE-2021-21973?

Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.

Does CVE-2021-21973 have an EU (EUVD) identifier?

Yes. CVE-2021-21973 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-9144. It is also flagged as exploited in the EUVD (since 2022-03-07).

When was CVE-2021-21973 published?

CVE-2021-21973 was published on 2021-02-24 and last updated on 2026-06-17.

CVE-2021-21973

CVE-2021-21973 is a medium-severity vulnerability in Vmware Cloud Foundation with a CVSS 3.x base score of 5.3. It is listed in CISA's Known Exploited Vulnerabilities (KEV) catalog, confirming it has been exploited in the wild (added 2022-03-07). The underlying weakness is classified as CWE-918.

Key facts

Severity: Medium (CVSS 3.x base score 5.3)
CVSS v2: 5.0
EPSS exploit prediction: 88% (100th percentile)
Actively exploited: Yes — listed in CISA KEV (added 2022-03-07)
EU (EUVD) id: EUVD-2021-9144
EU exploitation: Flagged exploited in the ENISA EU Vulnerability Database (since 2022-03-07)
Weakness: CWE-918
Affected product: Vmware Cloud Foundation
Published: 2021-02-24
Last modified: 2026-06-17

Description

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).

Frequently asked questions

What is CVE-2021-21973?: 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).
How severe is CVE-2021-21973?: CVE-2021-21973 has a CVSS 3.x base score of 5.3, rated medium severity. It is exploitable over network with low attack complexity, requires no privileges and no user interaction. Impact on confidentiality is low, integrity none, and availability none.
Is CVE-2021-21973 being actively exploited?: Yes. CVE-2021-21973 is on CISA's Known Exploited Vulnerabilities (KEV) catalog, added on 2022-03-07, which means active exploitation has been confirmed. It should be prioritised for remediation.
What products are affected by CVE-2021-21973?: CVE-2021-21973 primarily affects Vmware Cloud Foundation. In total, 42 product configurations (CPEs) are listed as vulnerable; see the affected-products list for the exact versions.
How do I fix CVE-2021-21973?: Review the linked vendor and NVD advisories for patched versions and mitigations, then upgrade or apply the recommended workaround. Because this CVE is known to be actively exploited, treat remediation as urgent — CISA KEV typically sets a short remediation deadline.
Does CVE-2021-21973 have an EU (EUVD) identifier?: Yes. CVE-2021-21973 is tracked in the ENISA EU Vulnerability Database (EUVD) as EUVD-2021-9144. It is also flagged as exploited in the EUVD (since 2022-03-07).
When was CVE-2021-21973 published?: CVE-2021-21973 was published on 2021-02-24 and last updated on 2026-06-17.

References

Affected products (42)

cpe:2.3:a:vmware:cloud_foundation:*:*:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:-:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:a:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:b:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:c:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:d:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:e:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:f:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:update1d:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:update1e:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:update1g:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:update2:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:update2b:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:update2c:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:update2d:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:update2g:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:update3:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:update3d:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:update3f:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.5:update3k:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.7:-:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.7:a:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.7:b:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.7:d:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.7:update1:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.7:update1b:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.7:update2:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.7:update2a:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.7:update2c:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.7:update3:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.7:update3a:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.7:update3b:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.7:update3f:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.7:update3g:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:6.7:update3j:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:7.0:-:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:7.0:a:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:7.0:b:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:7.0:c:*:*:*:*:*:*
cpe:2.3:a:vmware:vcenter_server:7.0:d:*:*:*:*:*:*

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