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MattermostApplication

CVE-2022-2406

MEDIUM · 6.5 CVSS v3.1 Published 2022-07-14
Fix available
A fix is available. Upgrade to after 6.5.1 or later.
See remediation →
71/100
Remediation priority · Elevated
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
The legacy Slack import feature in Mattermost version 6.7.0 and earlier fails to properly limit the sizes of imported files, which allows an authenticated attacker to crash the server by importing large files via the Slack import REST API.

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

The legacy Slack import feature in Mattermost versions 6.7.0 and earlier lacks proper file size validation on imported files. An authenticated attacker can send arbitrarily large files through the Slack import REST API, causing the server to exhaust resources and crash.

MitigationUpgrade Mattermost to a version newer than 6.7.0 which includes proper file size limits, or disable the legacy Slack import feature if not required.

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
MattermostApplication
Affected:<= 6.3.8>= 6.4.0, <= 6.5.1= 6.6.0= 6.6.1= 6.7.0

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

CVSS:3.1/AV:N/AC:L/PR:L/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 checks

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

  1. Check Mattermost server version
    Access the Mattermost system console or run 'grep -i version' in the Mattermost config file, or query the /api/v4/system/config endpoint if you have API access
    Affected if The installed version is 6.7.0 or earlier, specifically if it matches: <= 6.3.8; >= 6.4.0 through <= 6.5.1; or versions 6.6.0, 6.6.1, or 6.7.0
  2. Verify if legacy Slack import is enabled
    Check the Mattermost config.json file for the setting 'EnableSlackImport' or check via the System Console under Import/Export settings - look for Slack import functionality
    Affected if The legacy Slack import feature is currently enabled in the system configuration
  3. Check for unusual API activity on import endpoints
    Review Mattermost server logs for POST requests to /api/v4/import/slack or similar import endpoints, looking for excessive file sizes or frequency
    Affected if Logs show unusually large files being imported or high volume of import requests from authenticated users
  4. Monitor server resource consumption
    Check system resources (CPU, memory, disk I/O) on the Mattermost server host and look for patterns of resource exhaustion, particularly during import operations
    Affected if The server exhibits periodic or unexplained resource exhaustion that correlates with import operations

A user is affected if they are running any Mattermost version listed in the affected ranges AND have the legacy Slack import feature enabled, allowing authenticated users to trigger resource exhaustion through oversized file imports.

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 a release after 6.5.1
Interim mitigation

Upgrade Mattermost to a version newer than 6.7.0 which includes proper file size limits, or disable the legacy Slack import feature if not required.

Recommended fix High confidence

Mattermost 6.7.0 or later

  1. 1. Back up your Mattermost database and configuration files before upgrading.
  2. 2. Download the fixed Mattermost version (6.7.0 or later from mattermost.com/download).
  3. 3. Stop the Mattermost server.
  4. 4. Upgrade the Mattermost installation using your existing deployment method (e.g., apt upgrade, yum update, or manual tar.gz extraction).
  5. 5. Verify the server starts successfully and check system logs for any errors.
  6. 6. Test the Slack import functionality with a small test file to confirm the fix is working.
Caveat Review release notes for any changes to Slack import functionality or required configuration updates

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

Fix this in Mattermost 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
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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-2022-2406 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