CVE-2020-12026
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 · uneditedAdvantech WebAccess Node, Version 8.4.4 and prior, Version 9.0.0. Multiple relative path traversal vulnerabilities exist that may allow a low privilege user to overwrite files outside the application’s control.
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 confidenceMultiple path traversal vulnerabilities in Advantech WebAccess Node allow low-privilege authenticated users to write files outside the application's intended directory by manipulating file paths with relative path sequences (e.g., ../). This could enable privilege escalation or code execution if critical system files are overwritten.
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<= 8.4.4= 9.0.0CVSS 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
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- High
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:L/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 WebAccess versionLocate the WebAccess installation directory and check the version information file, typically found in the installation folder (often C:\Advantech\WebAccess or similar). Look for a version.txt, version.ini, or check the program files properties.Affected if The version is 8.4.4 or lower, or exactly 9.0.0
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Verify the web service is runningCheck if the Advantech WebAccess Node web service (typically named 'WebAccess Node' or 'Advantech WebAccess') is running. Open Services console (services.msc) and locate the service, or check if port 80/443 is listening.Affected if The web service is exposed and running, providing an attack surface for authenticated users
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Confirm low-privilege user authentication is enabledReview the WebAccess user management configuration (typically in the BADWORD or user configuration files within the installation). Check if accounts with limited (guest or operator-level) privileges can authenticate to the web interface.Affected if Low-privilege authenticated users can access the web interface, which is required to exploit the path traversal
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Locate file upload or write featuresExamine the WebAccess configuration for file upload, backup/restore, or project import functionalities. These are typically found under the system configuration or project management sections of the web interface.Affected if File upload, project import, or backup features are accessible to low-privilege users
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Test for path traversal filteringIf you have a test low-privilege account, attempt to use a file write function with a path containing ../ sequences (e.g., ../../../windows/system32/config). Observe whether the application rejects or accepts the path with traversal sequences.Affected if The application accepts relative path sequences (../) in file path parameters without validation, indicating the vulnerability is present
A system is affected if it runs Advantech WebAccess version 8.4.4 or lower, or exactly 9.0.0, and exposes the web interface to low-privilege authenticated users with file write capabilities that do not reject ../ sequences.
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 when available. In the interim, restrict file write permissions to the application, implement strict input validation on file path parameters to reject ../ sequences, and consider network segmentation to limit exposure of this ICS web application.
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Free · runs locallyCheck whether your project pulls in CVE-2020-12026 — 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-2020-12026 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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- Version or environment caveats, and links to real fixes
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