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ZammadApplication

CVE-2026-34721

MEDIUM · 6.5 CVSS v3.1 Published 2026-04-08
Fix available
A fix is available. Upgrade to 6.5.4 or later.
See remediation →
72/100
Remediation priority · Elevated
Remotely reachable No privileges

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 · unedited
Zammad is a web based open source helpdesk/customer support system. Prior to 7.0.1 and 6.5.4, the OAuth callback endpoints for Microsoft, Google, and Facebook external credentials do not validate a CSRF state parameter. 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 · high confidence

Zammad helpdesk system has a CSRF vulnerability in OAuth callback endpoints for Microsoft, Google, and Facebook integrations. The affected versions fail to validate the OAuth state parameter, which normally prevents CSRF attacks by ensuring the callback originates from a legitimate, user-initiated authentication request. An attacker could potentially trick a user into completing an OAuth flow that binds the user's account to the attacker's external identity provider account.

MitigationUpgrade Zammad to version 7.0.1 or 6.5.4 or later, which includes proper state parameter validation in OAuth callbacks. Verify all external authentication integrations (Microsoft, Google, Facebook) function correctly after upgrading.

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
ZammadApplication
Affected:< 6.5.4= 7.0.0

CVSS 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
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/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 checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Zammad version
    Access the Zammad web interface and navigate to Admin > System > Information, or run 'zammad --version' from the server command line, or check the installed package version via your package manager
    Affected if Version is less than 6.5.4 or equal to 7.0.0
  2. Identify OAuth external credential configuration
    Navigate to Admin > Settings > System > Third-party apps or Authentication settings in the Zammad web interface. Look for configured external credentials using OAuth with Microsoft, Google, or Facebook providers
    Affected if Any Microsoft, Google, or Facebook OAuth external credentials are enabled or configured in Zammad
  3. Verify OAuth flow susceptibility
    Review the OAuth callback URLs configured for external identity providers. The vulnerability exists in the callback endpoint handling after the OAuth provider redirects back to Zammad without proper state parameter validation
    Affected if External OAuth providers are configured and the installed version is in the affected range (less than 6.5.4 or exactly 7.0.0)

You are affected if your Zammad version is less than 6.5.4 or exactly 7.0.0 AND you have Microsoft, Google, or Facebook OAuth external credentials configured for user authentication

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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 · scoped
Upgrade available Upgrade to 6.5.4 or later
Fixed in 6.5.4
Interim mitigation

Upgrade Zammad to version 7.0.1 or 6.5.4 or later, which includes proper state parameter validation in OAuth callbacks. Verify all external authentication integrations (Microsoft, Google, Facebook) function correctly after upgrading.

Recommended fix High confidence

7.0.1 (for 7.x line) or 6.5.4 (for 6.x line)

  1. Identify your current Zammad version using your package manager or admin interface
  2. For Zammad 7.x users: Upgrade to version 7.0.1 or later
  3. For Zammad 6.x users: Upgrade to version 6.5.4 or later
  4. After upgrading, verify the OAuth configuration in Admin > System > External OAuth still works correctly
  5. Test OAuth login flows for Microsoft, Google, and Facebook external credentials to confirm the CSRF state parameter is now being validated

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Zammad Scoped from the published advisory
  • Consultation2.0 h
  • Implementation1.0 h
  • Testing3.0 h
  • Review / QA1.0 h
7.0 hours of engineering $1,210
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,936.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-34721 in production — separate from our analysis above.

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What this is

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.

What belongs here
  • 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