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Weekly Signal
Live intelligence Updated 20 Aug 2026 · 23:28 UTC

VMware · Cloud Foundation, vCenter Server, vCenter Server and Cloud Foundation

CVE-2021-21973

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

Recommended action

Validate affected assets and exposure now, then remediate on an accelerated schedule. VMware Security advisory VMSA-2021-0002

View response plan
CVSS5.3
EPSS87.6%
KEVYes
ExploitationConfirmed exploitation
RemediationNot yet verified ↓

Assessment

Why it matters

CISA lists this vulnerability as known to be exploited; exploitation is confirmed; EPSS is 87.6%; technical severity is CVSS 5.3.

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).

Who should care

  • Teams operating Cloud Foundation, vCenter Server, vCenter Server and Cloud Foundation
  • Vulnerability and exposure management teams
  • Security operations teams monitoring exploitation activity

Response plan

What I would do

  1. Confirm whether Cloud Foundation, vCenter Server, vCenter Server and Cloud Foundation is present in the environment.
  2. Identify affected versions and establish whether vulnerable services are exposed or reachable.
  3. VMware Security advisory VMSA-2021-0002
  4. Review relevant security telemetry for evidence of attempted or successful exploitation.
  5. Document the remediation decision and track it to verified completion.

Treatment intelligence

Remediation intelligence

Not yet verified

Vendor sources are listed before government and third-party guidance. Confirm product applicability and change prerequisites before deployment.

Verification noteAutomated link verification has not completed for this guidance yet.

Technical details

CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
CWE
CWE-20
Affected versions
VMware Cloud Foundation (Start Including 3.0, End Excluding 3.10.1.2 | Start Including 4.0, End Excluding 4.2); VMware vCenter Server (Version 6.5 | Version 6.5 | Version 6.5 | Version 6.5); VMware vCenter Server and Cloud Foundation
Fixed versions
VMware Cloud Foundation (Fixed from 3.10.1.2, 4.2)
Published
24 February 2021
Attack vector
Network
Privileges required
None
User interaction
None

Signal timeline

  1. CVE published
  2. Added to CISA KEV
  3. Latest EPSS score: 87.6%
  4. Signal calculated at 79

External references

Live public intelligence This assessment combines public-source evidence. Validate the affected product, version and exposure against your own environment before making a risk decision.