CVE-2021-40492
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 reflected XSS vulnerability exists in multiple pages in version 22 of the Gibbon application that allows for arbitrary execution of JavaScript (gibbonCourseClassID, gibbonPersonID, subpage, currentDate, or allStudents to index.php).
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 reflected cross-site scripting (XSS) vulnerability in Gibbon v22 allows attackers to inject arbitrary JavaScript via multiple GET parameters (gibbonCourseClassID, gibbonPersonID, subpage, currentDate, allStudents) passed to index.php without proper sanitization or output encoding.
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= 22.0.00CVSS 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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Identify Gibbon versionLocate the version file or check the Gibbon admin dashboard for the installed version number. Compare against the affected version 22.0.00.Affected if Installed version is exactly 22.0.00
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Confirm index.php is accessibleVerify the Gibbon web application index.php is accessible via HTTP/HTTPS at your installation path.Affected if index.php is publicly or internally accessible and accepts user input
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Check if vulnerable parameters are acceptedSubmit a test request to index.php with one of the affected GET parameters (gibbonCourseClassID, gibbonPersonID, subpage, currentDate, allStudents) containing a benign test string like 'test123'.Affected if The parameter and its value are reflected in the response without encoding or sanitization
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Verify output encoding is missingSubmit a request with a parameter value containing HTML/script characters (e.g., <script>alert(1)</script>) and examine if the response renders the raw characters literally or executes them.Affected if The special characters appear unencoded in the HTML output, indicating no output encoding is applied
If you are running Gibbon version 22.0.00 and the index.php page reflects user-supplied parameters without sanitization or encoding, your environment is affected by this XSS vulnerability.
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 for all user-supplied parameters in index.php and affected pages to prevent script injection.
- Consultation3.0 h
- Implementation6.0 h
- Testing3.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-40492 — 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-2021-40492 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