CVE-2017-18873
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 4.3.0, 4.2.1, and 4.1.2. It allows attackers to cause a denial of service (channel invisibility) via a misformatted post.
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 confidenceA denial of service vulnerability in Mattermost Server allows attackers to render channels invisible to users by submitting a specially formatted post. The vulnerability exists in versions prior to 4.3.0, 4.2.1, and 4.1.2.
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< 4.1.2>= 4.2.0, < 4.2.1= 4.3.0CVSS 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
- Low
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
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 installationLocate the Mattermost Server instance by checking running services, Docker containers, or the application hosting the Mattermost web interface.Affected if Mattermost Server is not present in the environment
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Determine the installed Mattermost Server versionAccess the Mattermost System Console and navigate to About > Mattermost, or use the Mattermost API endpoint /api/v4/system/brand/image, or check the version displayed in the server logs on startup.Affected if Unable to retrieve the version number for comparison
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Compare version against affected rangesCheck if the installed version falls into any of these vulnerable ranges: versions prior to 4.1.2, versions 4.2.0 through 4.2.0.x, or version exactly 4.3.0.Affected if The installed version is < 4.1.2, OR >= 4.2.0 and < 4.2.1, OR equals 4.3.0
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Verify post submission is exposedDetermine whether the server accepts posts from users who are not explicitly trusted, such as guest accounts, external integrators, or unauthenticated requests via webhook endpoints.Affected if Untrusted or external users can submit posts to channels
The environment is affected if Mattermost Server is running and its version matches < 4.1.2, >= 4.2.0 < 4.2.1, or exactly 4.3.0.
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 data4.1.24.2.1
Upgrade Mattermost Server to version 4.3.0, 4.2.1, 4.1.2 or later to patch the vulnerability. Prior to upgrade, consider input validation on posts or rate limiting to mitigate exploitation.
- Consultation1.0 h
- Implementation2.0 h
- Testing3.0 h
- Review / QA1.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-18873 — 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-2017-18873 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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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.
- 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