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MattermostApplication

CVE-2023-48268

HIGH · 7.5 CVSS v3.1 Published 2023-11-27
Fix available
A fix is available. Upgrade to after 9.0.1 or later.
See remediation →
84/100
Remediation priority · High
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 fails to limit the amount of data extracted from compressed archives during board import in Mattermost Boards allowing an attacker to consume excessive resources, possibly leading to Denial of Service, by importing a board using a specially crafted zip (zip bomb).

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 Boards fails to validate or limit the size of data extracted from zip archives during board import, allowing a specially crafted zip bomb (highly compressed file) to decompress to enormous sizes and exhaust server resources, causing Denial of Service.

MitigationImplement strict limits on the compression ratio and maximum extracted size when processing zip archives during board import, rejecting files that exceed reasonable thresholds.

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:<= 7.8.12>= 8.0.0, <= 8.1.3>= 9.0.0, <= 9.0.1= 9.1.0

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
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

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 Mattermost server version
    Run 'grep -i version /opt/mattermost/version.txt' or access Mattermost system console > About to view the version number
    Affected if Installed version falls within <= 7.8.12, 8.0.0-8.1.3, 9.0.0-9.0.1, or 9.1.0
  2. Verify Boards plugin is enabled
    Access System Console > Plugins > Plugin Management and confirm the 'focalboard' plugin is installed and enabled
    Affected if Boards plugin is enabled and running
  3. Confirm board import functionality is accessible
    Log in as a user, navigate to a Board, select 'Import' from the board menu, and verify the zip import option is available
    Affected if Users can import boards from zip archives through the Boards interface
  4. Check for anomalous resource consumption
    Monitor server disk space and memory during board import operations; review Mattermost server logs for out-of-memory errors or failed import operations involving zip files
    Affected if Server experiences resource exhaustion or fails during zip-based board imports

A Mattermost server is affected if it runs a version within the listed ranges AND has the Boards plugin enabled with board import functionality accessible to 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 a release after 9.0.1
Interim mitigation

Implement strict limits on the compression ratio and maximum extracted size when processing zip archives during board import, rejecting files that exceed reasonable thresholds.

Recommended fix Moderate confidence

7.8.13+, 8.1.4+, 9.0.2+, or 9.1.1+ (depending on your current major version line)

  1. 1. Identify the currently running Mattermost version using the system console or /about command
  2. 2. Based on your current version line, upgrade to the first version after your current major.minor release that includes the security fix
  3. 3. For Mattermost 7.8.x deployments, upgrade to version 7.8.13 or later
  4. 4. For Mattermost 8.0.x through 8.1.3 deployments, upgrade to version 8.1.4 or later
  5. 5. For Mattermost 9.0.x deployments, upgrade to version 9.0.2 or later
  6. 6. For Mattermost 9.1.0 deployments, upgrade to version 9.1.1 or later
  7. 7. After upgrade, verify the board import functionality works correctly
  8. 8. Consider restricting board import permissions to trusted users only as an additional precaution

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

Fix this in Mattermost Scoped from the published advisory
  • Consultation2.0 h
  • Implementation8.0 h
  • Testing4.0 h
  • Review / QA2.0 h
16.0 hours of engineering $2,800
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,480.

Scan for this in your stack

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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-2023-48268 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