CVE-2021-41563
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 · uneditedTad Book3 editing book function does not filter special characters. Unauthenticated attackers can remotely inject JavaScript syntax and execute stored XSS attacks.
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 · moderate confidenceTad Book3 contains a stored XSS vulnerability in its book editing function. The application fails to properly filter or sanitize special characters in user-supplied input when editing books, allowing unauthenticated remote attackers to inject malicious JavaScript code that persists on the server and executes in victim browsers.
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< 3.9CVSS 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 if Tad Book3 is installedCheck your web application inventory or search for Tad Book3 files in your web root directory. Look for directories or files containing 'tad_book3' or 'book3' in the application path.Affected if Tad Book3 is present in the environment
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Determine the installed versionLocate the version file or header typically found in the Tad Book3 installation directory. Common locations include a version.php, about.php, or changelog file within the Tad Book3 module directory.Affected if The version is lower than 3.9 (e.g., 3.8, 3.7, etc.)
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Verify the book editing function is accessibleCheck if the book editing module is enabled in the application. Look for the book editing URL path or administrative configuration that controls access to the book creation/editing feature.Affected if The book editing function is enabled and accessible to users
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Inspect input filtering in the book editing codeExamine the server-side code handling the book editing form submission. Look for input validation or sanitization functions applied to user input before storage, specifically checking if special characters (< > " ' script) are being filtered or encoded.Affected if No input filtering or sanitization is performed on user-supplied input in the book editing function
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Confirm stored XSS payload persistenceSubmit a test payload with special characters (e.g., <script>alert('XSS')</script>) through the book editing form, then retrieve the stored content to verify the payload is rendered without encoding.Affected if The malicious payload is stored and returned without proper encoding
The environment is affected if Tad Book3 version is below 3.9, the book editing function is enabled, and user input in the editing function is not properly sanitized before storage.
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.
dbcve · scoped3.9
Implement robust input validation and context-aware output encoding/escaping on all user input fields in the book editing function to neutralize malicious script payloads.
Tad Book3 version 3.9 or later
- Obtain Tad Book3 version 3.9 or later from the official source (www.twcert.org.tw or the project maintainer)
- Back up the current Tad Book3 installation and database
- Upgrade the existing installation to version 3.9 or later following the project's standard upgrade procedure
- Verify the upgrade was successful by checking the version number
- Test the book editing function to confirm XSS filtering is now properly applied
- Clear any cached data to ensure the new version is fully loaded
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation3.0 h
- Implementation8.0 h
- Testing4.0 h
- Review / QA2.0 h
An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,800.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-41563 — 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-2021-41563 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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