CVE-2021-20705
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 · uneditedImproper input validation vulnerability in the WebManager 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 file upload via 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 confidenceImproper input validation in the WebManager component of CLUSTERPRO/EXPRESSCLUSTER X 4.3 for Windows allows unauthenticated remote attackers to upload files via network. This could enable uploading of malicious files leading to remote code execution or other attacks.
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
- None
- Integrity
- High
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/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 installed ClusterPRO/Expresscluster product and versionOpen Windows Control Panel > Programs and Features, or use 'wmic product get name,version' command to list installed software. Look for 'Clusterpro X', 'Expresscluster X', or their Singleserversafe variants and note the version number.Affected if The installed version falls within the range 1.0 to 4.3 (any version from 1.0 through 4.3 is affected).
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Confirm WebManager component is enabledCheck if the WebManager service or feature is installed and running. This is typically accessible via the Cluster Manager interface or Windows services list. Look for services named 'Clusterpro WebManager' or similar.Affected if WebManager is installed and accessible on the network. The vulnerability requires the WebManager interface to be exposed.
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Verify WebManager network accessibilityCheck if port 29004 (default WebManager port) or any custom WebManager port is listening and accessible from the network. Use 'netstat -an | findstr 29004' or a port scanner to test external connectivity.Affected if The WebManager interface is reachable from untrusted networks. The vulnerability allows unauthenticated remote upload attacks.
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Inspect for unexpected files in WebManager directoriesLocate the WebManager document root or upload directories. Common locations include the Clusterpro installation folder under 'webmanager' or 'www' subdirectories. List all files and check for unexpected .asp, .aspx, .exe, .dll, or script files.Affected if Unexpected or malicious files exist in WebManager directories, indicating successful exploitation.
A user is affected if they have ClusterPRO/Expresscluster X version 4.3 or any version from 1.0 through 4.3 installed with the WebManager component enabled and accessible on the network.
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 patch when available. Until then, restrict network access to WebManager interface, implement web application firewall rules to block suspicious upload requests, and monitor for unauthorized file creation.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-20705 — 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-2021-20705 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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