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Mattermost ServerApplication · Mattermost

CVE-2025-0503

MEDIUM · 5.3 CVSS v3.1 Published 2025-02-14
Fix available
A fix is available. Upgrade to 9.11.7 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 9.11.x <= 9.11.6 fail to filter out DMs from the deleted channels endpoint which allows an attacker to infer user IDs and other metadata from deleted DMs if someone had manually marked DMs as deleted in the database.

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 9.11.x through 9.11.6 have an information disclosure vulnerability in the deleted channels endpoint. This endpoint fails to properly filter out direct messages (DMs) that were manually deleted in the database, allowing an authenticated attacker to infer user IDs and metadata from deleted DM conversations.

MitigationUpgrade Mattermost to version 9.11.7 or later. As a compensating control, audit database access permissions to prevent unauthorized manual deletions of DM records.

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:>= 9.11.0, < 9.11.7

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
Low
Integrity
None
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/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 installed Mattermost Server version
    Run 'mattermost version' or check the /api/v4/system/info endpoint, or look in the About section of the System Console
    Affected if The installed version is between 9.11.0 and 9.11.6 inclusive
  2. Verify access to the deleted channels API endpoint
    As an authenticated user, query the /api/v4/channels/deleted endpoint and examine the response for channel entries
    Affected if The endpoint returns DM channel entries that appear to have been manually deleted in the database (these should not appear)
  3. Inspect database for manually deleted DM records
    Query the database (PostgreSQL or MySQL) for Channels table entries where DeleteAt is set but the Type indicates a direct message (usually 'D' type)
    Affected if Any DM channel records exist in the database with a non-zero DeleteAt timestamp that are not properly filtered by the API
  4. Check API response for user ID leakage
    Compare API responses from /api/v4/channels/deleted between authenticated users with different permissions; note if user IDs or conversation metadata can be inferred from deleted DM entries that should not be visible
    Affected if Deleted DM channel entries expose other user IDs or conversation metadata that the requesting user should not have access to

A user is affected if their Mattermost Server version is 9.11.0 through 9.11.6 and the deleted channels API returns DM conversation entries that were manually deleted in the database, potentially leaking user IDs and metadata to unauthorized authenticated users.

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 9.11.7 or later
Fixed in 9.11.7
Interim mitigation

Upgrade Mattermost to version 9.11.7 or later. As a compensating control, audit database access permissions to prevent unauthorized manual deletions of DM records.

Recommended fix High confidence

9.11.7

  1. 1. Back up the Mattermost Server database and configuration files before upgrading.
  2. 2. Upgrade Mattermost Server from version 9.11.0-9.11.6 to version 9.11.7 using the official Mattermost upgrade process for your deployment method.
  3. 3. Verify the upgrade was successful by checking the server version and confirming the application is operational.

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
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $6,176.

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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-2025-0503 in production — separate from our analysis above.

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What this is

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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