CVE-2017-18881
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. XSS could occur via a goto_location response to a slash command.
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 before versions 4.3.0, 4.2.1, and 4.1.2 contains a reflected XSS vulnerability in the goto_location response handler for slash commands. User-supplied input in a slash command response is not properly sanitized before being rendered, allowing attackers to inject malicious JavaScript code that executes in the context of other users' browsers.
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
- Required
- Scope
- Changed
- Confidentiality
- Low
- Integrity
- Low
- Availability
- None
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/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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Locate Mattermost Server versionAccess the Mattermost System Console (usually at /admin_console) or check the /api/v4/system endpoint for the version string, or inspect the installation manifest if using a packaged versionAffected if The displayed version falls within < 4.1.2, >= 4.2.0 and < 4.2.1, or equals 4.3.0
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Confirm slash commands are enabledNavigate to Integrations > Slash Commands in the System Console and verify the 'Enable Slash Commands' setting is turned on, or query the config.json for the ServiceSettings.EnableSlashCommands settingAffected if Slash commands are enabled (the vulnerability cannot be exploited if this feature is disabled)
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Verify slash command integrations existReview the list of custom slash commands in Integrations > Slash Commands to see if any custom integrations are installed in the systemAffected if Custom slash command integrations exist that could return user-controlled content to the goto_location handler
Your system is affected if it runs any Mattermost Server version in the ranges < 4.1.2, >= 4.2.0 < 4.2.1, or exactly 4.3.0 AND has slash commands enabled with active integrations that could inject unsanitized content into the goto_location response handler.
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, or 4.1.2 or later. If immediate patching is not possible, disable or restrict untrusted slash commands and implement Content Security Policy headers as a compensating control.
- Consultation4.0 h
- Implementation2.0 h
- Testing4.0 h
- Review / QA2.0 h
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Scan for this in your stack
Free · runs locallyCheck whether your project pulls in CVE-2017-18881 — 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-2017-18881 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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