Cloud FoundationApplication · VMware
CVE-2021-21973
Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.
NVD · uneditedThe 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).
Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.
dbcve analysis · high confidenceCVE-2021-21973 is an SSRF (Server Side Request Forgery) vulnerability in the vSphere Client (HTML5) stemming from improper validation of URLs within a vCenter Server plugin. An unauthenticated attacker with network access to port 443 can send crafted POST requests to trigger the SSRF, potentially disclosing sensitive information from internal resources or the server itself.
Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.
Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.
NVD · CPE data
Cloud FoundationApplication
>= 3.0, < 3.10.1.2>= 4.0, < 4.2
Vcenter ServerApplication
= 6.5= 6.7= 7.0CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.
From the vector- Attack vector
- Network
- Complexity
- Low
- Privileges
- None
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N
Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.
dbcve checksWork through these to decide whether this CVE applies to you.
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Identify vCenter Server versionLocate the installed vCenter Server version through the vSphere Client about page, or run 'vpxd -v' on the vCenter Appliance, or check the VMware Product Lifecycle matrix for the specific 6.5, 6.7, or 7.0 build installedAffected if The installed version matches 6.5, 6.7, or 7.0 without the patched updates (U1c for 7.0, U3l for 6.7, U3n for 6.5)
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Identify Cloud Foundation versionLocate the installed Cloud Foundation version through the SDDC Manager console, or check the VMware Product Lifecycle matrix for the specific buildAffected if The installed version is 3.0 through 3.10.1.1, or 4.0 through 4.1, without the patched updates (4.2 or later, 3.10.1.2 or later)
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Verify network exposure of port 443Review firewall rules, security groups, or network ACLs to determine if port 443 on the vCenter Server is accessible from untrusted or external network segmentsAffected if Port 443 is exposed to untrusted or internet-facing network segments without restrictive access controls
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Inspect vCenter plugin endpointsReview the vCenter Server plugin configuration and accessible endpoints, particularly those handling URL validation in the HTML5 client interfaceAffected if The vCenter Server plugin URL validation endpoint is accessible and accepts arbitrary URLs without proper sanitization
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Check for suspicious POST requestsReview vCenter Server access logs and audit logs for anomalous POST requests to plugin endpoints, particularly those containing external or internal URL patternsAffected if Logs show POST requests to plugin endpoints with unusual URL parameters indicating potential SSRF exploitation attempts
A user is affected if their vCenter Server version is 6.5, 6.7, or 7.0 (or Cloud Foundation is 3.0-3.10.1.1 or 4.0-4.1) without the patched updates and port 443 is accessible to untrusted attackers
Generated from the published advisory. Verify against your own configuration.
Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.
dbcve · scoped3.10.1.24.2
Apply the vendor-supplied patches: upgrade vCenter Server to 7.0 U1c or later, 6.7 U3l or later, 6.5 U3n or later; upgrade Cloud Foundation to 4.2 or later or 3.10.1.2 or later. As an interim control, restrict network access to port 443 to trusted sources only.
vCenter Server 7.0 U1c, 6.7 U3l, or 6.5 U3n (or later); Cloud Foundation 4.2 or 3.10.1.2 (or later)
- 1. Schedule a maintenance window and back up the vCenter Server or Cloud Foundation appliance before proceeding
- 2. Download the appropriate update from VMware's download portal: vCenter Server 7.0 U1c (or later), 6.7 U3l (or later), 6.5 U3n (or later); Cloud Foundation 4.2 (or later), 3.10.1.2 (or later)
- 3. Apply the update using the vSphere UI or command-line tools (e.g., vamoi or the embedded update planner)
- 4. Verify the upgrade completed successfully by checking the vCenter Server/Cloud Foundation health status
- 5. Confirm the vulnerability is remediated by verifying the vCenter Server plugin no longer accepts unvalidated URLs
Generated from the published advisory — verify against the referenced sources before acting.
Fix this in Cloud Foundation
Exploited in the wild — priority engagement
- Consultation2.0 h
- Implementation4.0 h
- Testing3.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,088.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-21973 — or any other known-vulnerable package — straight from your lock files. Free and open source; it runs locally and uploads nothing.
References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.
Primary sourcesPractitioner notes
ContributedPeer-ranked notes from engineers who’ve handled CVE-2021-21973 in production — separate from our analysis above.
The advisory tells you what broke. It rarely tells you what actually worked. If you’ve dealt with this one, that detail is what the next engineer is searching for.
- The version that genuinely resolved it — not the one the vendor claimed
- A config change or rule that shut the vector down
- A gotcha in the upgrade path that cost you an afternoon
No notes yet
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- Verified mitigations, workarounds, and config changes
- Version or environment caveats, and links to real fixes
- No weaponised exploit code, or anything meant to cause harm
- No spam, self-promotion, credentials, or personal data