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Mattermost ServerApplication · Mattermost

CVE-2023-1775

MEDIUM · 6.5 CVSS v3.1 Published 2023-03-31
Fix available
A fix is available. Upgrade to 7.1.6 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
When running in a High Availability configuration, Mattermost fails to sanitize some of the user_updated and post_deleted events broadcast to all users, leading to disclosure of sensitive information to some of the users with currently connected Websocket clients.

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 · moderate confidence

In Mattermost High Availability configurations, the user_updated and post_deleted websocket events are broadcast to all connected users without proper sanitization, allowing sensitive information to be disclosed to unauthorized users who have active websocket connections.

MitigationApply the vendor-supplied patch or update Mattermost to a version that addresses this vulnerability; in the interim, consider restricting websocket access or reviewing HA configuration settings to limit event propagation.

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
High
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:N/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. Check installed Mattermost Server version
    Run 'grep -i version /opt/mattermost/version.go' or check the Mattermost System Console under About > Mattermost, or use the CLI: 'mattermost version'
    Affected if The version is less than 7.1.6 or exactly 7.7.1
  2. Verify High Availability configuration is enabled
    Check the config.json file for 'Enable' set to true in the 'Cluster' section, or view via System Console under Environment > High Availability
    Affected if High Availability (Cluster) settings are enabled in the Mattermost configuration
  3. Confirm websocket connections are active
    Check the 'Websocket' section of config.json for the 'AllowUnconnected' setting, or review active websocket connections via Mattermost logs or monitoring
    Affected if Websocket connections are permitted and active in the HA environment
  4. Review websocket event broadcasting settings
    Examine the Mattermost logs for user_updated or post_deleted events being broadcast, or inspect the websocket handler configuration in the Mattermost installation directory
    Affected if User_updated or post_deleted websocket events are being broadcast to users in an HA setup

The environment is affected if Mattermost Server version is less than 7.1.6 or exactly 7.7.1 AND High Availability clustering is enabled with active websocket connections.

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

Apply the vendor-supplied patch or update Mattermost to a version that addresses this vulnerability; in the interim, consider restricting websocket access or reviewing HA configuration settings to limit event propagation.

Recommended fix Moderate confidence

Upgrade to Mattermost Server 7.1.6 (or later 7.x version) or 7.7.2 (or later 7.x version) depending on your current branch

  1. 1. Identify current Mattermost Server version by checking the system console or running `mattermost version`
  2. 2. If running a version < 7.1.6, plan upgrade to version 7.1.6 or later
  3. 3. If running version 7.7.1, plan upgrade to version 7.7.2 or later
  4. 4. Review Mattermost upgrade documentation for your deployment type
  5. 5. Create a backup of the database and config file before upgrading
  6. 6. Perform the upgrade following Mattermost upgrade procedures
  7. 7. After upgrade, verify the system is functioning correctly and the WebSocket events are properly sanitized
Caveat Review Mattermost release notes for any breaking changes between your current version and target version before upgrading

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
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,130
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $3,408.

Scan for this in your stack

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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-2023-1775 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