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MattermostApplication

CVE-2023-5196

MEDIUM · 6.5 CVSS v3.1 Published 2023-09-29
Fix available
A fix is available. Upgrade to 7.8.10 / 8.0.2 or later.
See remediation →
71/100
Remediation priority · Elevated
Remotely reachable 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 enforce character limits in all possible notification props allowing an attacker to send a really long value for a notification_prop resulting in the server consuming an abnormal quantity of computing resources and possibly becoming temporarily unavailable for its users.

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 · moderate confidence

Mattermost fails to enforce character limits on notification properties, allowing an attacker to send arbitrarily long values in notification_prop fields. This causes excessive server resource consumption (CPU, memory, storage) potentially leading to temporary service unavailability.

MitigationImplement server-side input validation with strict character length limits on all notification property fields to prevent resource exhaustion attacks.

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:>= 7.0.0, < 7.8.10>= 8.0.0, < 8.0.2>= 8.1.0, < 8.1.1

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

CVSS:3.1/AV:N/AC:L/PR:L/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. Determine Mattermost server version
    Run 'mattermost version' from the command line, or query the API endpoint /api/v4/system/analytics?name=version, or check the About section in the System Console
    Affected if The installed version falls within >= 7.0.0 and < 7.8.10, OR >= 8.0.0 and < 8.0.2, OR >= 8.1.0 and < 8.1.1
  2. Identify notification_prop data in the database
    Query the Posts table in the Mattermost database for rows where notification_prop contains unusually large or long JSON content (e.g., values exceeding normal length)
    Affected if Records exist with notification_prop field values that are abnormally large (several KB or more), indicating potential exploitation
  3. Monitor server resource usage
    Check CPU, memory, and storage usage on the Mattermost server, particularly database storage growth patterns
    Affected if Resources are being consumed at abnormally high rates or database storage is growing unexpectedly due to large notification_prop entries

You are affected if your Mattermost server version is 7.0.0 through 7.8.9, 8.0.0 through 8.0.1, or 8.1.0, and there are unusually large notification_prop values stored in the database or excessive resource consumption is observed.

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 7.8.10 / 8.0.2 / 8.1.1 or later
Fixed in 7.8.108.0.28.1.1
Interim mitigation

Implement server-side input validation with strict character length limits on all notification property fields to prevent resource exhaustion attacks.

Recommended fix High confidence

7.8.10, 8.0.2, or 8.1.1 (depending on your current major version line)

  1. 1. Back up your Mattermost database and configuration files before upgrading.
  2. 2. Review the Mattermost Upgrade Guide at https://docs.mattermost.com/upgrade/upgrading-mattermost-server.html for your deployment method.
  3. 3. For Docker deployments: Pull the new image tag (e.g., mattermost/mattermost:7.8.10, mattermost/mattermost:8.0.2, or mattermost/mattermost:8.1.1) and recreate containers.
  4. 4. For mattermost-mmctl or team deployments: Download the appropriate Mattermost Server release from https://releases.mattermost.com/ and follow the upgrade procedure.
  5. 5. After upgrade, verify that the Mattermost server starts successfully and users can connect.
  6. 6. Test notification functionality to confirm normal operation.
Caveat Check release notes for each version for potential breaking changes; minor version upgrades within the same major version typically have minimal breaking changes

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
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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-2023-5196 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