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Mattermost ServerApplication · Mattermost

CVE-2025-9079

HIGH · 7.2 CVSS v3.1 Published 2025-09-19
Fix available
A fix is available. Upgrade to 9.11.18 / 10.5.9 or later.
See remediation →
78/100
Remediation priority · High
Remotely reachable 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
Mattermost versions 10.8.x <= 10.8.3, 10.5.x <= 10.5.8, 9.11.x <= 9.11.17, 10.10.x <= 10.10.1, 10.9.x <= 10.9.3 fail to validate import directory path configuration which allows admin users to execute arbitrary code via malicious plugin upload to prepackaged plugins directory

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 fails to validate the import directory path configuration, allowing administrator users to upload malicious plugins to the prepackaged plugins directory. This improper path validation enables arbitrary code execution on the server through crafted plugin uploads.

MitigationUpgrade to a patched version of Mattermost (10.8.4, 10.5.9, 9.11.18, 10.10.2, or 10.9.4 or later) or apply vendor-supplied patches. Restrict admin access and monitor for unauthorized plugin uploads in the interim.

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:>= 9.11.0, < 9.11.18>= 10.5.0, < 10.5.9>= 10.8.0, < 10.8.4>= 10.9.0, < 10.9.4>= 10.10.0, < 10.10.2

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
High
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:H/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. Check installed Mattermost Server version
    Run 'mattermost version' or check the version displayed in the system console under About > Mattermost
    Affected if The installed version falls within any of these ranges: 9.11.0-9.11.17, 10.5.0-10.5.8, 10.8.0-10.8.3, 10.9.0-10.9.3, or 10.10.0-10.10.1
  2. Verify admin access to plugin import functionality
    Log in as a system administrator and navigate to Plugins > Marketplace or Plugins > Uploads to see if the import or upload interface is accessible
    Affected if Administrator users can access plugin upload or import functionality in the UI
  3. Inspect import directory path configuration
    Check the Mattermost config.json for 'ImportSettings' or 'PluginSettings' related to directory paths, or view System Console > Plugins > Plugin Management for path configurations
    Affected if An import directory path is configured and accessible to admin users without proper validation
  4. Review plugin directory for unexpected files
    Examine the prepackaged plugins directory (typically under /opt/mattermost/plugins or the configured plugins directory) for any unexpected or recently added plugin bundles
    Affected if There are plugin files present that were not part of the original Mattermost installation or were added after the suspected vulnerable version upgrade

A user is affected if they run a Mattermost Server version within the affected ranges listed and have administrator accounts that can access plugin import or upload functionality.

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 9.11.18 / 10.5.9 / 10.8.4 or later
Fixed in 9.11.1810.5.910.8.4
Interim mitigation

Upgrade to a patched version of Mattermost (10.8.4, 10.5.9, 9.11.18, 10.10.2, or 10.9.4 or later) or apply vendor-supplied patches. Restrict admin access and monitor for unauthorized plugin uploads in the interim.

Recommended fix High confidence

Upgrade to 9.11.18 (for 9.11.x), 10.5.9 (for 10.5.x), 10.8.4 (for 10.8.x), or 10.9.4 (for 10.9.x) depending on your current branch

  1. 1. Backup your Mattermost Server data and configuration before upgrading.
  2. 2. Identify your current Mattermost Server version by navigating to System Console > About.
  3. 3. Download the appropriate fixed version for your current major version from the official Mattermost downloads page: https://releases.mattermost.com/
  4. 4. For Mattermost 9.11.x: Upgrade to version 9.11.18
  5. 5. For Mattermost 10.5.x: Upgrade to version 10.5.9
  6. 6. For Mattermost 10.8.x: Upgrade to version 10.8.4
  7. 7. For Mattermost 10.9.x: Upgrade to version 10.9.4
  8. 8. Follow the standard Mattermost upgrade procedure for your deployment method (manual, Docker, or mattermostctl).
Caveat Standard patch upgrade - review release notes for any deprecation notices in minor releases

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

Fix this in Mattermost Server Scoped from the published advisory
  • Consultation3.0 h
  • Implementation6.0 h
  • Testing4.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,640
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,224.

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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-2025-9079 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