CVE-2026-34718
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 · uneditedZammad is a web based open source helpdesk/customer support system. Prior to 7.0.1 and 6.5.4, the HTML sanitizer for ticket articles was missing proper sanitization of data: ... URI schemes, resulting in storing such malicious content in the database of the Zammad instance. The Zammad GUI is rendering this content, due to applied CSP rules no harm was done by e.g., clicking such a link. This vulnerability is fixed in 7.0.1 and 6.5.4.
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 confidenceStored XSS vulnerability in Zammad's HTML sanitizer for ticket articles. The sanitizer failed to properly sanitize URI schemes, allowing malicious content to be stored in the database. While Content Security Policy rules provided partial protection against click-based exploitation, the vulnerability still represents a security risk.
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< 6.5.4= 7.0.0CVSS 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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Identify Zammad versionCheck the installed Zammad version via web UI (footer or admin panel) or by running 'zammad --version' from the command line, or inspect the package manager if installed via apt/yumAffected if Version is lower than 6.5.4 or exactly 7.0.0
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Verify ticket article HTML sanitizer is in useConfirm that Zammad is processing ticket articles with HTML content. This is a default feature enabled for handling rich text in tickets.Affected if The system processes HTML-formatted ticket articles (this is the default behavior)
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Check for data URI content in ticket articlesQuery the database for ticket articles containing 'data:' URI schemes in HTML content. In PostgreSQL: SELECT id, article_type FROM tickets WHERE content LIKE '%data:%' LIMIT 10;Affected if Any ticket article contains a data: URI scheme in its HTML content (this indicates potential malicious payload)
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Review database for stored XSS patternsInspect ticket article content in the database for suspicious patterns like data:text/html, data:image/svg+xml, or other data URIs that could contain JavaScript or HTML payloadsAffected if Records contain data URIs with embedded script tags, event handlers, or iframe sources
A system is affected if it runs Zammad versions lower than 6.5.4 or exactly 7.0.0 and processes ticket articles with HTML content, regardless of whether CSP blocks exploitation from user interaction.
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 · scoped6.5.4
Upgrade Zammad to version 7.0.1 or 6.5.4 to apply the patched HTML sanitizer that properly sanitizes URI schemes in ticket articles.
6.5.4 (for 6.x line) or 7.0.1 (for 7.x line)
- Backup your Zammad database and configuration files before proceeding
- Check your current Zammad version using the admin interface or command line
- If running Zammad 7.0.0, upgrade to version 7.0.1
- If running a version earlier than 6.5.4 in the 6.x line, upgrade to version 6.5.4
- Follow the standard Zammad upgrade documentation for your deployment method (package manager, Docker, or source)
- After upgrade, verify the HTML sanitizer is working correctly by testing with sample ticket articles containing various URI schemes
- Confirm the admin interface shows the corrected version number
Generated from the published advisory — verify against the referenced sources before acting.
- Consultation1.0 h
- Implementation2.0 h
- Testing2.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2026-34718 — 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-2026-34718 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