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Mattermost ServerApplication · Mattermost

CVE-2026-3113

MEDIUM · 5.5 CVSS v3.1 Published 2026-03-26
Fix available
A fix is available. Upgrade to 10.11.12 / 11.2.4 or later.
See remediation →
57/100
Remediation priority · Elevated
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 11.4.x <= 11.4.0, 11.3.x <= 11.3.1, 11.2.x <= 11.2.3, 10.11.x <= 10.11.11 fail to set permissions on downloaded bulk export which allows other local users on the server to be able to read contents of the bulk export.. Mattermost Advisory ID: MMSA-2026-00593

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 fails to set secure file permissions on downloaded bulk export files, leaving them readable by other local users on the server. This allows local privilege escalation where any user with shell access can read sensitive bulk export data containing potentially confidential information.

MitigationUpgrade Mattermost to the latest patched version or ensure proper umask/file permissions (600 or stricter) are applied to the export download directory and files.

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:>= 10.11.0, < 10.11.12>= 11.2.0, < 11.2.4>= 11.3.0, < 11.3.2= 11.4.0

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
Local
Complexity
Low
Privileges
Low
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
None
Availability
None

CVSS:3.1/AV:L/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 'mattermost version' or check the version displayed in the system console under About > Mattermost
    Affected if The version matches >=10.11.0 and <10.11.12, OR >=11.2.0 and <11.2.4, OR >=11.3.0 and <11.3.2, OR equals 11.4.0
  2. Locate bulk export files on the server
    Search for files named with 'export' in the Mattermost data directory, typically under /var/opt/mattermost/data/ or the configured DataDirectory path; look for .zip or .json files related to bulk exports
    Affected if Bulk export files exist on the server filesystem
  3. Verify file permissions on export files
    Run 'ls -la' on the export files or the export download directory; check if other users have read access (permissions should not show 'r--r--r--' or similar for group/other)
    Affected if Files are readable by other local users (permissions include 'r--' for group or 'r--' for others, or directory allows world-readable access)
  4. Check umask configuration for the Mattermost process
    Review the systemd service file or init script for the umask setting: grep -i umask /etc/systemd/system/mattermost.service or similar; default umask of 022 results in 644 permissions
    Affected if Umask is set to a permissive value like 022 or 002, resulting in group/other readable files

A user is affected if their Mattermost Server version is in the affected list AND bulk export files exist on the server with overly permissive file permissions readable by other local 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 10.11.12 / 11.2.4 / 11.3.2 or later
Fixed in 10.11.1211.2.411.3.2
Interim mitigation

Upgrade Mattermost to the latest patched version or ensure proper umask/file permissions (600 or stricter) are applied to the export download directory and files.

Recommended fix High confidence

Upgrade to 10.11.12 (for 10.11.x), 11.2.4 (for 11.2.x), 11.3.2 (for 11.3.x), or 11.4.1 (for 11.4.0)

  1. Identify the currently installed Mattermost Server version using 'mmctl version' or the system console
  2. For Mattermost 10.11.x: Upgrade to version 10.11.12 or later
  3. For Mattermost 11.2.x: Upgrade to version 11.2.4 or later
  4. For Mattermost 11.3.x: Upgrade to version 11.3.2 or later
  5. For Mattermost 11.4.0: Upgrade to version 11.4.1 or later
  6. After upgrade, verify the fix by downloading a bulk export and checking file permissions (should be restrictive, e.g., 0600 or similar restricted permissions)
Caveat Standard upgrade considerations apply - review release notes for any configuration or feature changes between versions

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
  • Testing4.0 h
  • Review / QA2.0 h
18.0 hours of engineering $3,200
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $5,120.

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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-2026-3113 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