CVE-2021-27436
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 · uneditedWebAccess/SCADA Versions 9.0 and prior is vulnerable to cross-site scripting, which may allow an attacker to send malicious JavaScript code to an unsuspecting user, which could result in hijacking of the user’s cookie/session tokens, redirecting the user to a malicious webpage and performing unintended browser actions.
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 confidenceWebAccess/SCADA versions 9.0 and prior contains a cross-site scripting (XSS) vulnerability that allows attackers to inject malicious JavaScript code. This stored XSS executes in victim browsers, enabling session cookie theft, redirection to malicious sites, and unauthorized browser 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<= 9.0CVSS 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
- 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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Confirm WebAccess/SCADA installationCheck for the Advantech WebAccess/SCADA service or web application on the system. Look for the web server running on common ports (for example, ports 80/443 or the default SCADA web port). Use netstat or similar tools to identify if a WebAccess web service is listening.Affected if WebAccess/SCADA web service is found running on the system
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Identify installed versionAccess the web interface login page or an 'About' section within the WebAccess/SCADA application to determine the exact version number. If the web UI is not accessible, check the installed software version through the system registry or installed programs list.Affected if Version is 9.0 or lower (or version cannot be determined and the product is present)
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Verify web interface accessibilityConfirm the WebAccess/SCADA web portal is accessible over the network. Attempt to reach the login page or user-facing web pages through a browser or HTTP request.Affected if The web interface is reachable and the version is 9.0 or prior
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Check for unauthenticated input pointsIdentify user-supplied input fields within the WebAccess/SCADA web application that could accept and store data. These typically include forms for tag names, descriptions, project settings, or user profile fields.Affected if User input fields exist in the web application and version is 9.0 or prior
The environment is affected if Advantech WebAccess/SCADA version 9.0 or prior is installed and its web interface is accessible, as the stored XSS vulnerability exists in user-supplied input handling within this version range.
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 dataImplement input validation and output encoding on all user-supplied data, applyContent Security Policy (CSP) headers to restrict script execution, and apply vendor patches when available.
- Consultation6.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,816.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-27436 — 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-2021-27436 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
- No spam, self-promotion, credentials, or personal data