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Mattermost ServerApplication · Mattermost

CVE-2024-22091

MEDIUM · 6.5 CVSS v3.1 Published 2024-04-26
Fix available
A fix is available. Upgrade to 8.1.12 / 9.5.3 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 versions 8.1.x <= 8.1.10, 9.6.x <= 9.6.0, 9.5.x <= 9.5.2 and 8.1.x <= 8.1.11 fail to limit the size of a request path that includes user inputs which allows an attacker to cause excessive resource consumption, possibly leading to a DoS via sending large request paths

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 validate or limit the length of request paths containing user-supplied input. An attacker can send HTTP requests with excessively large path segments, causing the server to consume excessive resources (CPU, memory, or network) processing these unbounded paths, potentially leading to denial of service.

MitigationUpgrade to Mattermost 8.1.11, 9.5.3, 9.7.0 or later to receive the patch. Alternatively, implement request size/path length limits at the load balancer or reverse proxy to reject oversized request paths before they reach the application.

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:>= 8.1.0, < 8.1.12>= 9.5.0, < 9.5.3>= 9.6.0, < 9.6.1

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. Identify installed Mattermost Server version
    Run 'mattermost version' or check the version file in the Mattermost installation directory (e.g., /opt/mattermost/version.txt)
    Affected if The version is >= 8.1.0 and < 8.1.12, OR >= 9.5.0 and < 9.5.3, OR >= 9.6.0 and < 9.6.1
  2. Check if a reverse proxy or load balancer is present
    Inspect the network configuration and look for nginx, Apache, HAProxy, or cloud load balancer configurations sitting in front of Mattermost
    Affected if No reverse proxy or load balancer exists, or one exists but has no path/length restrictions configured
  3. Verify request path length limits at the proxy
    For nginx, check 'client_max_body_size' and 'large_client_header_buffers' directives in the nginx.conf. For Apache, check 'LimitRequestFieldSize' and 'LimitRequestLine'. For HAProxy, check 'http-request deny' rules with path length conditions
    Affected if No limit is configured to reject HTTP requests with excessively large path segments before they reach Mattermost
  4. Check Mattermost native rate limiting
    Examine Mattermost config.json for 'RateLimitSettings' section, specifically looking for any path-based rate limiting configuration
    Affected if No application-level path length restrictions are defined and the server version falls within the affected ranges

You are affected if your Mattermost Server version is within the affected ranges AND oversized request paths can reach the application without being blocked by an upstream proxy or application-level limit.

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 8.1.12 / 9.5.3 / 9.6.1 or later
Fixed in 8.1.129.5.39.6.1
Interim mitigation

Upgrade to Mattermost 8.1.11, 9.5.3, 9.7.0 or later to receive the patch. Alternatively, implement request size/path length limits at the load balancer or reverse proxy to reject oversized request paths before they reach the application.

Recommended fix High confidence

Mattermost Server 8.1.12 (or later in 8.1.x), 9.5.3 (or later in 9.5.x), or 9.6.1 (or later in 9.6.x)

  1. Identify the currently running Mattermost Server version using the system console or mmctl command
  2. Determine which version branch your current installation falls into (8.1.x, 9.5.x, or 9.6.x)
  3. Backup the Mattermost database and configuration files before upgrading
  4. For 8.1.x deployments: upgrade to version 8.1.12 or later
  5. For 9.5.x deployments: upgrade to version 9.5.3 or later
  6. For 9.6.x deployments: upgrade to version 9.6.1 or later
  7. Follow the standard Mattermost upgrade documentation for your deployment method (docker, helm, or manual)
  8. After upgrade, verify the server starts successfully and the system console shows the new version
Caveat Standard Mattermost upgrade considerations apply - review release notes for any breaking changes between your current and target versions, particularly around database migrations and plugin compatibility

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

Fix this in Mattermost Server 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
Get the upgrade done

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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-2024-22091 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