CVE-2021-38408
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 · uneditedA stack-based buffer overflow vulnerability in Advantech WebAccess Versions 9.02 and prior caused by a lack of proper validation of the length of user-supplied data may allow remote code execution.
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 confidenceA stack-based buffer overflow vulnerability exists in Advantech WebAccess versions 9.02 and prior. The vulnerability is caused by insufficient validation of user-supplied data length before copying it into a fixed-size stack buffer. This memory corruption flaw can be exploited by remote attackers to execute arbitrary code on the affected system.
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<= 9.02CVSS 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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Confirm Advantech WebAccess installationCheck for WebAccess installation directories (typically in C:\Advantech\WebAccess or C:\Program Files\Advantech\WebAccess) or look for WebAccess services in Windows Services listAffected if Advantech WebAccess software is found on the system
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Identify installed WebAccess versionLocate version information in the installation directory, check file properties of main executables (such as BWS.exe, Node.exe, or similar), or query the Windows Registry under HKLM\SOFTWARE\Advantech\WebAccess for the Version keyAffected if Installed version is 9.02 or any version prior to 9.02
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Verify web service is running and exposedCheck if the WebAccess Windows service (typically named 'Advantech WebAccess Service' or similar) is running, and identify if TCP ports 80/443 or custom ports used by WebAccess are listeningAffected if WebAccess service is running and the web interface is accessible on the network (the vulnerability is remotely exploitable)
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Inspect input handling pointsReview web access logs (typically in the WebAccess\LOG directory) for unusual request patterns or anomalies that may indicate exploitation attempts targeting the buffer overflowAffected if Log evidence shows suspicious requests with unusually large data payloads to input fields
The environment is affected if Advantech WebAccess version 9.02 or earlier is installed and the web service is accessible and running.
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 dataUpgrade Advantech WebAccess to a version beyond 9.02 that includes proper bounds checking. If immediate patching is not possible, restrict network access to the WebAccess interface and implement input validation at network boundaries.
- Consultation2.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA3.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2021-38408 — 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-2021-38408 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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