CVE-2021-35301
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 · uneditedIncorrect Access Control in Zammad 1.0.x up to 4.0.0 allows remote attackers to obtain sensitive information via the Ticket Article detail view.
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 confidenceZammad help desk software versions 1.0.x through 4.0.0 contains an incorrect access control vulnerability in the Ticket Article detail view. Remote unauthenticated attackers can exploit this flaw to access sensitive information they should not be authorized to view, such as internal ticket communications or customer data.
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
- None
- Scope
- Unchanged
- Confidentiality
- Low
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/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 Zammad installationCheck for Zammad installation by looking for the application directory (typically /opt/zammad, /srv/zammad, or in the web server root), or run 'zammad --version' if the CLI is available. On systems with package managers, check installed packages with 'dpkg -l | grep zammad' or 'rpm -qa | grep zammad'.Affected if Zammad is found installed on the system
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Determine installed Zammad versionCheck the version by reviewing the Gemfile.lock or package version file in the Zammad directory, or query the API endpoint '/api/v1/health' which returns version information in the response, or check the admin interface System > Information page.Affected if The version is >= 1.0.0 and <= 4.0.0
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Verify unauthenticated access to ticket articlesTest if the Ticket Article detail API endpoint '/api/v1/ticket_articles/{id}' is accessible without authentication by sending a request with no valid session or API token. Attempt to access article IDs directly without logging in.Affected if The API responds with ticket article data (internal communications, customer data) without requiring authentication
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Check authentication configurationReview Zammad configuration files (typically in /opt/zammad/config or environment variables) for settings related to 'guest_login', 'public_access', or session authentication requirements. Verify if the web interface permits unauthenticated access to ticket views.Affected if Guest or public access is enabled, or authentication is not enforced on ticket article endpoints
The environment is affected if Zammad version 1.0.0 through 4.0.0 is installed AND the ticket article detail API or web view is accessible to unauthenticated users.
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 4.0.1 or later. If immediate patching is not possible, review and restrict network access to the Zammad instance and implement additional access control layers at the web application firewall level.
- Consultation4.0 h
- Implementation8.0 h
- Testing6.0 h
- Review / QA4.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2021-35301 — 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-2021-35301 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