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Mattermost DesktopApplication · Mattermost

CVE-2026-1046

MEDIUM · 6.5 CVSS v3.1 Published 2026-02-16
Fix available
A fix is available. Upgrade to 5.13.3 / 6.0.3 or later.
See remediation →
72/100
Remediation priority · Elevated
Remotely reachable No privileges

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 Desktop App versions <=6.0 6.2.0 5.2.13.0 fail to validate help links which allows a malicious Mattermost server to execute arbitrary executables on a user’s system via the user clicking on certain items in the Help menu Mattermost Advisory ID: MMSA-2026-00577

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

The Mattermost Desktop App fails to validate help links before executing them, allowing a malicious or compromised Mattermost server to supply crafted URLs that trigger execution of arbitrary executables on the user's system when they interact with Help menu items.

MitigationUpdate Mattermost Desktop App to a patched version beyond 6.2.0/5.2.13.0. Users should only connect to trusted Mattermost servers to avoid exploitation by malicious servers.

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 DesktopApplication
Affected:>= 5.13.2, < 5.13.3>= 6.0.0, < 6.0.3

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
Required
Scope
Unchanged
Confidentiality
None
Integrity
High
Availability
None

CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:N/I:H/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 Desktop version
    Open the app, go to Help > About Mattermost Desktop (or check your system-installed applications list) to find the exact version number
    Affected if Version is 5.13.2 through 5.13.2.x, or 6.0.0 through 6.0.2.x (versions 5.13.3+ and 6.0.3+ are patched)
  2. Determine if custom server connections are allowed
    Launch Mattermost Desktop and check if you can add a custom server URL (not just connect to mattermost.com). Look for 'Add custom server' or similar option in server connection settings
    Affected if Custom server URLs can be added - the vulnerability requires a malicious server to supply the crafted help links
  3. Identify connected Mattermost servers
    Review your Mattermost Desktop client for all server connections (check server list or configuration)
    Affected if You are connected to any third-party or self-hosted Mattermost servers that you do not fully control or trust

You are affected if you run an affected version (5.13.2 to 5.13.2.x or 6.0.0 to 6.0.2.x) AND have the ability to connect to custom Mattermost servers, including any servers you do not trust completely.

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 5.13.3 / 6.0.3 or later
Fixed in 5.13.36.0.3
Interim mitigation

Update Mattermost Desktop App to a patched version beyond 6.2.0/5.2.13.0. Users should only connect to trusted Mattermost servers to avoid exploitation by malicious servers.

Recommended fix High confidence

Mattermost Desktop 5.13.3 (for 5.x users) or 6.0.3 (for 6.x users)

  1. 1. Open Mattermost Desktop and navigate to the app menu (three dots or File menu)
  2. 2. Click on 'Help' > 'About Mattermost' to view the current version number
  3. 3. If running version 5.13.2 or earlier in the 5.x line, download version 5.13.3 from the official Mattermost downloads page
  4. 4. If running version 6.0.0-6.0.2 in the 6.x line, download version 6.0.3 from the official Mattermost downloads page
  5. 5. Close the current Mattermost Desktop application completely
  6. 6. Run the installer for the downloaded fixed version
  7. 7. Restart the application and verify the version in 'Help' > 'About Mattermost' shows the updated release

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

Fix this in Mattermost Desktop Scoped from the published advisory
  • Consultation2.0 h
  • Implementation4.0 h
  • Testing3.0 h
  • Review / QA2.0 h
11.0 hours of engineering $1,930
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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-2026-1046 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