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CVE-2021-21973

MEDIUM
5.3
CVSS Score
Published: February 24, 2021 at 04:42 PM UTC
Updated: June 17, 2026 at 03:36 AM UTC
2 products affected across 1 vendorCloud FoundationvCenter Server

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Severity
MEDIUM5.3
Exploitation
CISA KEV
Exploit prediction
EPSS 88%
SSVC
Active

Actively Exploited

CISA Known Exploited Vulnerabilities (KEV) Catalog

EPSS Score88.0%

EPSS (Exploit Prediction Scoring System) estimates a 88.0% chance this CVE is exploited in the wild within the next 30 days — higher than 100% of all CVEs. It complements CVSS: a high EPSS on a mid-severity CVE can still be urgent.

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.

Required Action
Apply updates per vendor instructions.
Ransomware Use
Unknown
Added to KEV
Mar 7, 2022
Remediation Due
Mar 21, 2022
1684 days overdue
Notes
https://nvd.nist.gov/vuln/detail/CVE-2021-21973

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).

Affected

Our own answer: ranges merged, affected separated from platform-only, with confidence and review flags.

Cloud Foundation· VMware
95%
3 ≤ v < 3.10.1.23.0 ≤ v < 3.10.1.24 ≤ v < 4.24.0 ≤ v < 4.2
Affected range stops below 3.10.1.2, so it looks safe — our inference, not a vendor statement
Affected range stops below 4.2, so it looks safe — our inference, not a vendor statement
vCenter Server· VMware
95%
v < 6.5v < 6.7v < 7.06.56.5 a6.5 b6.5 c6.5 d6.5 e6.5 f6.5 update1d6.5 update1e6.5 update1g6.5 update26.5 update2b6.5 update2c6.5 update2d6.5 update2g6.5 update36.5 update3d6.5 update3f6.5 update3k6.76.7 a6.7 b6.7 d6.7 update16.7 update1b6.7 update26.7 update2a6.7 update2c6.7 update36.7 update3a6.7 update3b6.7 update3f6.7 update3g6.7 update3j7.07.0 a7.0 b7.0 c7.0 d7.0 update17.0 update1a
Affected range stops below 6.5, so it looks safe — our inference, not a vendor statement
Affected range stops below 6.7, so it looks safe — our inference, not a vendor statement
Affected range stops below 7.0, so it looks safe — our inference, not a vendor statement

Remediation

No guide yet

No remediation guidance has been written for this CVE yet. What the record does show:

Patch and advisory references

References (2)

x_refsource_CONFIRMVendor Advisory
Source: [email protected]
https://www.vmware.com/security/advisories/VMSA-2021-0002.html
US Government Resource
Source: 134c704f-9b21-4f2e-91b3-4a467353bcc0
https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-21973

SSVC — Action Prioritization

SSVCActiveAutomatablePartial impact

SSVC signals action urgency (what to patch first), separate from CVSS which measures severity.

CVSS

5.3MEDIUMCISA-ADP
Attack Vector
NETWORK
Complexity
LOW
Privileges
NONE
User Interaction
NONE
Scope
UNCHANGED
Confidentiality
LOW
Integrity
NONE
Availability
NONE
Vector?

Quick Info

StatusANALYZED
CWE
CWE-918

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