CVE-2021-22676
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 · uneditedUserExcelOut.asp within WebAccess/SCADA is vulnerable to cross-site scripting (XSS), which could allow an attacker to send malicious JavaScript code. This could result in hijacking of cookie/session tokens, redirection to a malicious webpage, and unintended browser action on the WebAccess/SCADA (WebAccess/SCADA versions prior to 8.4.5, WebAccess/SCADA versions prior to 9.0.1).
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 confidenceCross-site scripting (XSS) vulnerability in UserExcelOut.asp within Advantech WebAccess/SCADA allows attackers to inject malicious JavaScript code through the application, which executes in victims' browsers to steal session cookies, redirect users, or perform unauthorized actions.
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< 8.4.5>= 9.0, < 9.0.1CVSS 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
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/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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Verify Advantech WebAccess/SCADA installationLocate the WebAccess installation directory on the system, typically found under C:\Advantech\WebAccess or C:\Program Files\Advantech\WebAccessAffected if The software is not installed or the installation directory cannot be found
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Determine installed WebAccess/SCADA versionCheck the version of Advantech WebAccess/SCADA by reviewing installation files, registry entries, or the application's about/version informationAffected if The installed version is less than 8.4.5, or greater than or equal to 9.0 but less than 9.0.1
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Locate vulnerable UserExcelOut.asp fileSearch for the UserExcelOut.asp file within the WebAccess installation directory, typically under the \scada\ or \bwscada\ subdirectoryAffected if The UserExcelOut.asp file exists in the installation directory
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Confirm web server is serving the vulnerable scriptCheck if the IIS web server or embedded web server is running and the WebAccess web application is accessible via HTTP/HTTPSAffected if The web interface is active and the UserExcelOut.asp script can be accessed remotely
A system is affected if Advantech WebAccess/SCADA is installed with a version less than 8.4.5 or between 9.0 and 9.0.1 (exclusive), and the UserExcelOut.asp file is present and accessible via the web interface.
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 data8.4.59.0.1
Update WebAccess/SCADA to version 8.4.5 or later (for 8.x branch) or 9.0.1 or later (for 9.x branch). Apply input validation and output encoding as defense-in-depth measures.
- Consultation3.0 h
- Implementation4.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-22676 — 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-2021-22676 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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A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.
- 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