Is CVE-2021-21973 in the CISA KEV catalog?

Yes. CVE-2021-21973 is on the CISA Known Exploited Vulnerabilities list, added 2022-03-07.

What is the CVSS severity of CVE-2021-21973?

CVE-2021-21973 has a CVSS v3 base score of 5.3 (MEDIUM).

What is the EPSS score for CVE-2021-21973?

CVE-2021-21973 has an EPSS score of 88.01% (100th percentile), estimating the probability of exploitation in the next 30 days.

CVE & CISA-KEV Catalog

CVE-2021-21973

MEDIUMCISA KEVEPSS 100th pctl

5.3

CVSS v3

NVD

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).

CWE-918Server-Side Request Forgery (SSRF)

CVSS v3 Vector

Exploitability

Attack VectorNetwork

Attack ComplexityLow

Privileges RequiredNone

User InteractionNone

ScopeUnchanged

Impact

ConfidentialityLow

IntegrityNone

AvailabilityNone

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

Exploit Intelligence

88.01%probability of exploitation in 30 days

100thpercentile

Very high risk: more likely to be exploited than 100% of all known CVEs.

Known Exploited Vulnerability (CISA KEV)

VMware vCenter Server and Cloud Foundation Server Side Request Forgery (SSRF) Vulnerability

VMware vCenter Server and Cloud Foundation Server contain a SSRF vulnerability due to improper validation of URLs in a vCenter Server plugin. This allows for information disclosure.

Apply updates per vendor instructions.

Remediation due: 2022-03-21

References

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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2025-10-30.