CVE-2021-20704
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 · uneditedBuffer overflow vulnerability in the compatible API with previous versions CLUSTERPRO X 4.3 for Windows and earlier, EXPRESSCLUSTER X 4.3 for Windows and earlier, CLUSTERPRO X 4.3 SingleServerSafe for Windows and earlier, EXPRESSCLUSTER X 4.3 SingleServerSafe for Windows and earlier allows attacker to remote code execution via a network.
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 · moderate confidenceBuffer overflow vulnerability in the backward-compatible API layer of CLUSTERPRO X and EXPRESSCLUSTER X 4.3 for Windows and earlier allows remote attackers to execute arbitrary code via network exploitation of the overflow.
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>= 1.0, <= 4.3>= 1.0, <= 4.3>= 1.0, <= 4.3>= 1.0, <= 4.3CVSS 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
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
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 installed product and versionOpen Windows Control Panel > Programs and Features, or right-click the installed Clusterpro/Expresscluster executable and view Properties > Details to find the version number. Compare against the affected range 1.0 to 4.3.Affected if The installed version is 4.3 or earlier (1.0 through 4.3 inclusive).
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Confirm backward-compatible API is enabledAccess the cluster management console or configuration tool. Navigate to the API or interface settings section. Look for an option related to 'backward-compatible API', 'legacy API', or 'compatible API' mode.Affected if The backward-compatible API feature is explicitly enabled or left in default enabled state.
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Check network exposure of management interfacesReview firewall rules or network configuration to determine if the cluster management port (typically port 29001 or similar) is exposed to untrusted networks or accessible from external IP addresses.Affected if The management interface listening port is reachable from network segments that contain untrusted or external hosts.
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Verify Windows platformConfirm the operating system is Windows, as this vulnerability specifically affects the Windows version of the affected products.Affected if Running on Windows with Clusterpro X or Expresscluster X installed.
A system is affected if it runs version 4.3 or earlier of Clusterpro X or Expresscluster X on Windows, has the backward-compatible API enabled, and has the management interface exposed to network access.
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.
From vendor dataApply vendor patches or updates to versions beyond 4.3; if patching is immediately unavailable, restrict network access to the cluster management interfaces and disable the compatible API feature if not required.
- Consultation4.0 h
- Implementation8.0 h
- Testing12.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20704 — 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-2021-20704 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
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