CVE-2021-35298
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 · uneditedCross Site Scripting (XSS) in Zammad 1.0.x up to 4.0.0 allows remote attackers to execute arbitrary web script or HTML via multiple models that contain a 'note' field to store additional information.
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 confidenceStored Cross-Site Scripting (XSS) vulnerability in Zammad help desk software allows remote attackers to inject malicious JavaScript or HTML through the 'note' field present in multiple database models. The vulnerability affects versions 1.0.x through 4.0.0 and is exploitable when user-supplied content in note fields is rendered without proper sanitization.
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>= 1.0.0, <= 4.0.0CVSS 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
- 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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Determine installed Zammad versionRun command: zammad --version or check the About page in the Zammad web UI under Admin > System > InformationAffected if Version is 1.0.0 through 4.0.0 inclusive
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Verify Zammad is runningConfirm the Zammad web application is accessible and the backend services (rails, nginx, postgresql) are runningAffected if The application is operational and exposes note field functionality
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Identify note field usageCheck database models that contain note fields: examine tables like users, organizations, groups, or any custom object that includes a note attribute. Use SQL query: SELECT table_name FROM information_schema.columns WHERE column_name LIKE '%note%';Affected if Note fields exist in any active database models and are accessible to users
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Confirm note fields accept user inputLog into Zammad as a regular user or agent and attempt to create or edit an object that contains a note field (such as user profiles, organizations, or tickets with note attributes)Affected if User-supplied content can be saved into note fields and later rendered without sanitization
If Zammad version is between 1.0.0 and 4.0.0 inclusive and note fields are present and functional in the system, the environment is vulnerable to stored XSS via CVE-2021-35298.
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 dataUpgrade Zammad to version 4.1.0 or later which contains the security patch. Alternatively, implement server-side input validation and output encoding for all note fields to neutralize XSS payloads before storage and rendering.
- Consultation2.0 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 $4,480.
Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-35298 — 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-2021-35298 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