CVE-2020-26029
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 · uneditedAn issue was discovered in Zammad before 3.4.1. There are wrong authorization checks for impersonation requests via X-On-Behalf-Of. The authorization checks are performed for the actual user and not the one given in the X-On-Behalf-Of header.
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 before 3.4.1 contains an authorization flaw where the X-On-Behalf-Of header allows user impersonation, but authorization checks are incorrectly performed on the requesting user rather than the target user specified in the header. This enables authenticated users to potentially perform actions as other users they should not have access to impersonate.
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, < 3.4.1CVSS 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
- Low
- User interaction
- None
- Scope
- Unchanged
- Confidentiality
- High
- Integrity
- None
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/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 checksWork through these to decide whether this CVE applies to you.
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Determine installed Zammad versionRun `zammad --version` from the command line, check the web interface under Admin > System > About, or query the package manager (dpkg/rpm) if installed via system packagesAffected if Version is 1.0.0 or higher but lower than 3.4.1
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Identify if X-On-Behalf-Of feature is in useReview HTTP requests and application logs for occurrences of the X-On-Behalf-Of header, or check API documentation and integration configs for any reference to this headerAffected if The X-On-Behalf-Of header is being used to specify target users in API calls
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Verify authorization behavior for impersonationUsing an authenticated session, attempt to send a request with the X-On-Behalf-Of header pointing to a different user account and observe whether the action executes under the target user's context without proper authorization validationAffected if Actions are performed as the target user in the header rather than being rejected due to insufficient permissions on the requesting user's side
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Confirm web server or API gateway configurationInspect the web server (nginx/apache) configuration and any reverse proxy settings to ensure the X-On-Behalf-Of header is being passed through to the Zammad applicationAffected if The header is not being stripped or filtered before reaching the application
You are affected if your Zammad version is 1.0.0 through 3.4.0 and the X-On-Behalf-Of header is being used in your environment, allowing authenticated users to bypass authorization checks.
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 data3.4.1
Upgrade Zammad to version 3.4.1 or later to obtain the fixed authorization logic for X-On-Behalf-Of header processing.
- Consultation2.0 h
- Implementation4.0 h
- Testing6.0 h
- Review / QA2.0 h
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Free · runs locallyCheck whether your project pulls in CVE-2020-26029 — 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-2020-26029 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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- Version or environment caveats, and links to real fixes
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