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MattermostApplication

CVE-2024-39830

MEDIUM · 5.9 CVSS v3.1 Published 2024-07-03
Fix available
A fix is available. Upgrade to 9.5.6 / 9.6.3 or later.
See remediation →
68/100
Remediation priority · Elevated
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
Mattermost versions 9.8.x <= 9.8.0, 9.7.x <= 9.7.4, 9.6.x <= 9.6.2 and 9.5.x <= 9.5.5, when shared channels are enabled, fail to use constant time comparison for remote cluster tokens which allows an attacker to retrieve the remote cluster token via a timing attack during remote cluster token comparison.

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 versions 9.5.x through 9.8.x contain a timing side-channel vulnerability in the remote cluster token comparison logic used by shared channels. The application uses a non-constant-time string comparison (e.g., == or !=) instead of a constant-time comparison function, allowing an attacker to incrementally deduce the remote cluster token by measuring response time differences during authentication attempts.

MitigationUpgrade Mattermost to versions 9.8.1, 9.7.5, 9.6.3, or 9.5.6 or later. If immediate patching is not possible, consider disabling shared channels or restricting network exposure to the remote cluster interface.

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:>= 9.5.0, < 9.5.6>= 9.6.0, < 9.6.3>= 9.7.0, < 9.7.5>= 9.8.0, < 9.8.1

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

CVSS:3.1/AV:N/AC:H/PR:N/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. Identify Mattermost server version
    Run the command `mattermost version` or check the system console under About > Mattermost to view the currently installed version number
    Affected if The version falls within 9.5.0 to 9.5.5, 9.6.0 to 9.6.2, 9.7.0 to 9.7.4, or 9.8.0 to 9.8.0 (i.e., any version from 9.5.0 up to but not including 9.5.6, 9.6.3, 9.7.5, or 9.8.1)
  2. Confirm shared channels feature status
    Check if the Shared Channels feature is enabled in the system console under Channels > Shared Channels, or query the server configuration via the Mattermost API or config file
    Affected if Shared channels are enabled and the server is configured to act as a remote cluster node with a shared channel token configured
  3. Locate remote cluster token configuration
    Inspect the Mattermost configuration file (config.json) or the environment variables for any configured RemoteCluster or SharedChannel settings that include an authentication token
    Affected if A remote cluster token is defined in the configuration for shared channel synchronization between Mattermost instances

You are affected if your Mattermost server version is 9.5.0 through 9.5.5, 9.6.0 through 9.6.2, 9.7.0 through 9.7.4, or 9.8.0, AND shared channels with remote cluster communication are enabled with a token configured.

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 9.5.6 / 9.6.3 / 9.7.5 or later
Fixed in 9.5.69.6.39.7.5
Interim mitigation

Upgrade Mattermost to versions 9.8.1, 9.7.5, 9.6.3, or 9.5.6 or later. If immediate patching is not possible, consider disabling shared channels or restricting network exposure to the remote cluster interface.

Recommended fix High confidence

Upgrade to 9.5.6, 9.6.3, 9.7.5, or 9.8.1 depending on your current version branch

  1. Identify current Mattermost version by checking the system console or running 'mattermost version'
  2. Determine which version branch you are on (9.5.x, 9.6.x, 9.7.x, or 9.8.x)
  3. For version 9.5.x: upgrade to 9.5.6 or later
  4. For version 9.6.x: upgrade to 9.6.3 or later
  5. For version 9.7.x: upgrade to 9.7.5 or later
  6. For version 9.8.x: upgrade to 9.8.1 or later
  7. After upgrade, verify the version via the system console or CLI
  8. If shared channels are not needed, consider disabling them as a temporary mitigation until upgrade is complete
Caveat Review Mattermost upgrade notes for potential database migration requirements and breaking changes between minor versions

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

Fix this in Mattermost Scoped from the published advisory
  • Consultation1.0 h
  • Implementation2.0 h
  • Testing2.0 h
  • Review / QA1.0 h
6.0 hours of engineering $1,040
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $1,664.

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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-2024-39830 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