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MattermostApplication

CVE-2024-36257

MEDIUM · 5.3 CVSS v3.1 Published 2024-07-03
Fix available
A fix is available. Upgrade to 9.5.6 or later.
See remediation →
62/100
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 9.5.x <= 9.5.5 and 9.8.0, when using shared channels with multiple remote servers connected, fail to check that the remote server A requesting the server B to update the profile picture of a user is the remote that actually has the user as a local one . This allows a malicious remote A to change the profile images of users that belong to another remote server C that is connected to the server A.

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 9.5.5 and 9.8.0 contain an improper validation vulnerability in the shared channels feature. When multiple remote servers are interconnected, the system fails to verify that a remote server requesting a profile picture update is the legitimate owner of that user. This allows a malicious remote server A to manipulate profile images of users belonging to a different remote server C connected to server A.

MitigationUpgrade to a patched version of Mattermost (newer than 9.5.5 and 9.8.0). If immediate upgrade is not possible, consider disabling shared channels or restricting which remote servers can connect until the patch can be applied.

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= 9.8.0

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

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/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. Determine installed Mattermost version
    Access the Mattermost System Console and navigate to About > Mattermost, or check the version via the /api/v4/system endpoint. Compare the version number against the affected ranges: 9.5.0 through 9.5.5 and version 9.8.0.
    Affected if The installed version is 9.5.0, 9.5.1, 9.5.2, 9.5.3, 9.5.4, 9.5.5, or 9.8.0
  2. Verify shared channels feature is enabled
    In the Mattermost System Console, go to Environment > Web Server or look for Shared Channels settings. Alternatively, check the config.json file for the 'RemoteCluster' or 'SharedChannels' setting.
    Affected if Shared channels or remote cluster functionality is enabled in the configuration
  3. Identify connected remote servers
    In the System Console, navigate to Users > Remote Cluster or Integration > Shared Channels to view the list of connected remote servers. Note how many remote servers are interconnected.
    Affected if Two or more remote servers are connected through the shared channels feature

A user is affected if their Mattermost version is 9.5.0-9.5.5 or 9.8.0, shared channels are enabled, and multiple remote servers are interconnected.

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 or later
Fixed in 9.5.6
Interim mitigation

Upgrade to a patched version of Mattermost (newer than 9.5.5 and 9.8.0). If immediate upgrade is not possible, consider disabling shared channels or restricting which remote servers can connect until the patch can be applied.

Recommended fix High confidence

9.5.6 or later for 9.5.x branch; 9.8.1 or later for 9.8.x branch

  1. 1. Identify the current Mattermost server version by checking the system console or running 'mattermost version'
  2. 2. If running 9.5.0 through 9.5.5, upgrade to Mattermost 9.5.6 or later
  3. 3. If running 9.8.0, upgrade to the next available stable release (9.8.1 or later)
  4. 4. Before upgrading, backup the database and configuration files
  5. 5. Review Mattermost upgrade documentation for your deployment type (hot reload, rolling, or full restart)
  6. 6. Perform the upgrade following standard Mattermost upgrade procedures
  7. 7. After upgrade, verify that shared channels functionality works correctly
Caveat Check 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 Scoped from the published advisory
  • Consultation4.0 h
  • Implementation16.0 h
  • Testing12.0 h
  • Review / QA6.0 h
38.0 hours of engineering $6,560
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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-2024-36257 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