CVE-2019-20869
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 Mattermost Server before 5.10.0, 5.9.1, 5.8.2, and 4.10.9. A non-member could change the Update/Patch Channel endpoint for a private channel.
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 confidenceMattermost Server had an broken access control vulnerability where the Update/Patch Channel API endpoint (PUT /channels/{id}) did not properly enforce authorization checks, allowing non-members to modify settings of private channels they did not belong to. This is a privilege escalation issue in the channel permission model.
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< 4.10.9>= 5.7.0, < 5.7.3>= 5.8.0, < 5.8.2>= 5.9.0, < 5.9.1= 5.10.0CVSS 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
- None
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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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Check Mattermost Server versionRun the command: curl -s http://localhost:8065/api/v4/system/stats | grep -i version or check the About section in the Mattermost UI under Account Settings > General > Version. Alternatively, check the installed package version using your package manager (e.g., dpkg -l mattermost-server or rpm -qi mattermost-server).Affected if The installed version matches one of the affected ranges: < 4.10.9, >= 5.7.0 and < 5.7.3, >= 5.8.0 and < 5.8.2, >= 5.9.0 and < 5.9.1, or exactly 5.10.0
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Verify API access is enabledCheck the Mattermost configuration file (config.json) for the EnableAPIv3 or EnableTesting settings. Ensure the API endpoint /api/v4/channels/{id} is accessible. Review the ServiceSettings section of the config file.Affected if API v3 or v4 is enabled and exposed to untrusted users, which is the default configuration for most Mattermost installations
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Identify private channels in the systemUse the Mattermost UI to view all channels and identify those marked as Private, or query the database directly: SELECT name, displayname, type FROM channels WHERE type = 'P'Affected if Private channels exist in the system, as these are the channel type vulnerable to unauthorized modification by non-members
A user is affected if they run a Mattermost Server version within the affected ranges AND have private channels configured, as non-members could exploit the PUT /channels/{id} API endpoint to modify private channel settings.
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 data4.10.95.7.35.8.2
Upgrade Mattermost Server to version 5.10.0, 5.9.1, 5.8.2, 4.10.9 or later. These versions include proper authorization validation for the channel update endpoint to ensure only channel members can modify private channel properties.
- Consultation1.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2019-20869 — 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-2019-20869 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
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