CVE-2019-20854
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 5.17.0. It allows remote attackers to cause a denial of service (client-side application crash) via a LaTeX message.
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 confidenceMattermost Server before version 5.17.0 contains a vulnerability where specially crafted LaTeX messages sent through the server cause the client-side application to crash, resulting in denial of service for affected users.
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< 5.17.0CVSS 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
- None
- Availability
- High
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
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 Mattermost Server installationCheck for Mattermost Server processes running on the system (e.g., ps aux | grep mattermost) or look for installation directories such as /opt/mattermost or /var/opt/mattermostAffected if Mattermost Server is not found or not running
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Determine installed Mattermost Server versionRun 'mattermost version' from the Mattermost bin directory, or check the version file typically located at /opt/mattermost/version.txt or within the Mattermost logsAffected if The installed version is lower than 5.17.0 (e.g., 5.16.x, 5.15.x, etc.)
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Check if LaTeX rendering is enabledExamine the Mattermost configuration file (config.json) for the 'Latex' or 'EnableLatex' setting under the 'TeamSettings' or 'ServiceSettings' section, or check via the System Console under Posts > Enable LaTeX renderingAffected if LaTeX rendering is enabled and the server version is below 5.17.0
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Verify exposed Mattermost web interfaceConfirm the Mattermost Server web interface is accessible externally or internally by accessing the login page via browser or checking network listeners (e.g., netstat -tlnp | grep 8065)Affected if The server is accessible and running a vulnerable version with LaTeX enabled
You are affected if Mattermost Server version is below 5.17.0 AND the LaTeX rendering feature is enabled, as this combination allows specially crafted LaTeX messages to crash client applications.
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 data5.17.0
Upgrade Mattermost Server to version 5.17.0 or later to remediate this vulnerability.
- Consultation2.0 h
- Implementation3.0 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-2019-20854 — 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-2019-20854 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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