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Mattermost ServerApplication · Mattermost

CVE-2017-18912

CRITICAL · 9.8 CVSS v3.1 Published 2020-06-19
Fix available
A fix is available. Upgrade to 3.6.7 / 3.7.5 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

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 · unedited
An issue was discovered in Mattermost Server before 3.8.2, 3.7.5, and 3.6.7. It allows an attacker to specify a full pathname of a log file.

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 confidence

Mattermost Server before 3.8.2, 3.7.5, and 3.6.7 contains a path traversal vulnerability allowing attackers to specify an arbitrary full pathname for log files. This could enable writing log content to unintended locations, potentially leading to remote code execution if log files are written to web-accessible directories, or file overwrite/denial-of-service conditions.

MitigationUpgrade Mattermost Server to version 3.8.2, 3.7.5, 3.6.7 or later. If immediate patching is not possible, restrict server access and monitor for suspicious log configuration requests.

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
Mattermost ServerApplication
Affected:< 3.6.7>= 3.7.0, < 3.7.5>= 3.8.0, < 3.8.2

CVSS 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
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/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 checks

Work through these to decide whether this CVE applies to you.

  1. Identify Mattermost Server version
    Check the version file or config.json in the Mattermost installation directory, or run 'mattermost version' if the CLI is available
    Affected if The installed version is less than 3.6.7, OR between 3.7.0 and 3.7.4 inclusive, OR between 3.8.0 and 3.8.1 inclusive
  2. Locate the Mattermost configuration file
    Find config.json in the Mattermost root directory or /opt/mattermost/config/
    Affected if Cannot locate the configuration file to inspect settings
  3. Examine logging configuration settings
    Open config.json and look for 'LogSettings' or 'LogFile' configuration entries that define log file paths
    Affected if Log file path settings are present and can be set to arbitrary paths (the vulnerable condition)
  4. Check file system permissions on log directory
    Verify whether the configured log directory or the Mattermost web root is writable by the application
    Affected if The application can write to web-accessible directories, which would enable the RCE scenario described in the CVE

The server is affected if the installed Mattermost Server version falls within the vulnerable ranges (<3.6.7, 3.7.0-3.7.4, or 3.8.0-3.8.1) AND log file path configuration is accessible to untrusted users.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

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.

dbcve · scoped
Upgrade available Upgrade to 3.6.7 / 3.7.5 / 3.8.2 or later
Fixed in 3.6.73.7.53.8.2
Interim mitigation

Upgrade Mattermost Server to version 3.8.2, 3.7.5, 3.6.7 or later. If immediate patching is not possible, restrict server access and monitor for suspicious log configuration requests.

Recommended fix High confidence

Mattermost Server 3.8.2 (or 3.7.5 / 3.6.7 depending on compatibility needs)

  1. Identify the current Mattermost Server version by checking the system console or running 'mattermost version'
  2. Plan upgrade path based on your current version - upgrade to 3.6.7, 3.7.5, or 3.8.2 (recommended)
  3. Back up the Mattermost database and configuration files before upgrading
  4. Stop the Mattermost Server service
  5. Install the appropriate fixed version of Mattermost Server (3.8.2 recommended for latest features and security fixes)
  6. Restart the Mattermost Server service
  7. Verify the upgrade was successful by checking the version in the system console
Caveat Review Mattermost upgrade notes for migration considerations when moving between minor versions

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Mattermost Server Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing2.0 h
  • Review / QA1.0 h
9.0 hours of engineering $1,600
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $2,560.

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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2017-18912 in production — separate from our analysis above.

No notes yet

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What this is

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.

What belongs here
  • 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