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Mattermost ServerApplication · Mattermost

CVE-2023-1774

MEDIUM · 5.4 CVSS v3.1 Published 2023-03-31
Fix available
A fix is available. Upgrade to 7.1.6 or later.
See remediation →
60/100
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
When processing an email invite to a private channel on a team, Mattermost fails to validate the inviter's permission to that channel, allowing an attacker to invite themselves to a private channel.

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 that the inviter has permission to add members to a private channel during email invite processing. An authenticated attacker with team access but lacking channel-level permissions can exploit this authorization bypass to invite themselves to private channels they should not access.

MitigationImplement permission validation in the invite processing logic to verify the inviter has appropriate channel membership or roles before allowing invitations to private channels.

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:< 7.1.6= 7.7.1

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
Low
Integrity
Low
Availability
None

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

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

  1. Identify installed Mattermost Server version
    Access the Mattermost System Console and navigate to About > Edition/Version, or use the CLI: `mattermost version` or check the /opt/mattermost/version file
    Affected if The version number is lower than 7.1.6 or exactly equal to 7.7.1
  2. Confirm email invitations are enabled
    Navigate to System Console > User Management > Users > Enable Email Invitations, or check the configuration file (config.json) for "EnableEmailInvitations": true
    Affected if Email invitations are enabled and the server version is in the affected range
  3. Identify existing private channels
    Use Mattermost CLI: `mattermost channel list --team <team_name>` and check channels with "private" scope, or via System Console > Channels > Private Channels
    Affected if Private channels exist and the server version is in the affected range with email invitations enabled
  4. Review team member roles versus channel permissions
    Check user membership in private channels via System Console > Users > Channel Membership, or use API: GET /channels/{channel_id}/members to compare team-level access against private channel membership
    Affected if Users exist with team membership who are NOT members of private channels within that team

Your environment is affected if running Mattermost Server version 7.1.6 or below, or exactly version 7.7.1, with email invitations enabled and private channels present where non-member team users could self-invite.

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 7.1.6 or later
Fixed in 7.1.6
Interim mitigation

Implement permission validation in the invite processing logic to verify the inviter has appropriate channel membership or roles before allowing invitations to private channels.

Recommended fix Moderate confidence

Mattermost Server 7.1.6 or later (or 7.8.0+ to include fixes beyond 7.7.1)

  1. 1. Back up your Mattermost Server database and configuration files.
  2. 2. Download Mattermost Server version 7.1.6 or later from the official Mattermost downloads page (mattermost.com).
  3. 3. Stop the Mattermost Server service.
  4. 4. Upgrade the Mattermost Server installation using the standard upgrade process for your deployment method (e.g., apt-get upgrade, yum update, or manual upgrade).
  5. 5. Verify the upgrade was successful by checking the server version in the system console.
  6. 6. Restart the Mattermost Server service.
  7. 7. Test that private channel invite functionality works correctly and that proper authorization checks are enforced.
Caveat Review Mattermost release notes for version 7.1.6+ for any configuration or feature changes that may affect your deployment

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

Fix this in Mattermost Server Scoped from the published advisory
  • Consultation4.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
22.0 hours of engineering $3,860
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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-2023-1774 in production — separate from our analysis above.

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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