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Path TraversalWeakness · CWE-22

CVE-2026-13426

MEDIUM · 5.4 CVSS v3.1 Published 2026-06-26
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
See remediation →
60/100
Remediation priority · Elevated
Remotely reachable Zero-click 8 weeks old

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
The Mattermost Go module github.com/mattermost/mattermost/server/public versions < v0.1.22 fail to validate path parameters when constructing API route paths which allows an attacker to redirect API calls to unintended endpoints via crafted IDs containing path traversal components. Mattermost Advisory ID: MMSA-2025-00532

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 Go module github.com/mattermost/mattermost/server/public fails to validate path parameters when constructing API route paths, allowing crafted IDs containing path traversal sequences (e.g., '../') to redirect API calls to unintended endpoints.

MitigationUpgrade the mattermost server/public module to v0.1.22 or later which implements proper path parameter validation.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

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
Low
Integrity
Low
Availability
None

CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/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. Locate the Go module dependency
    Inspect the go.mod file in your Mattermost deployment and search for the line containing 'github.com/mattermost/mattermost/server/public'. Note the version specified after the module name.
    Affected if The version listed is below v0.1.22 or there is no version specified (using latest master/main branch).
  2. Identify API route definitions using path parameters
    Search the codebase for route definitions that include path parameters, such as patterns like '/api/v4/teams/{team_id}/...' or '/channels/{channel_id}/...'. Look in router or route registration files.
    Affected if The application defines API routes that accept path parameters ( curly brace syntax like {id} or :id ) without explicit validation.
  3. Check for path traversal validation in parameter handling
    Review the code that handles extracted path parameters before constructing API calls. Look for functions that parse route parameters and validate them before use in URL construction.
    Affected if There is no validation logic that strips or rejects path traversal sequences (../, ..\) from path parameters before they are used in API route construction.
  4. Verify runtime dependency version
    Run 'go list -m all' or inspect the vendor directory to confirm the exact version of mattermost/server/public module that is actually being used at build time.
    Affected if The resolved version is below v0.1.22.

Your environment is affected if the mattermost/server/public module version is below v0.1.22 AND your deployment exposes API endpoints that accept path parameters without validation.

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
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Upgrade the mattermost server/public module to v0.1.22 or later which implements proper path parameter validation.

Recommended fix High confidence

github.com/mattermost/mattermost/server/public v0.1.22 or later

  1. Locate the go.mod file in your project that declares dependency on github.com/mattermost/mattermost/server/public
  2. Update the module reference to version v0.1.22 or later (e.g., change 'require github.com/mattermost/mattermost/server/public v0.1.21' to 'require github.com/mattermost/mattermost/server/public v0.1.22')
  3. Run 'go mod tidy' to update dependencies and verify the upgrade succeeds
  4. Rebuild and redeploy your application with the updated dependency
  5. Verify that API routes correctly handle path parameters and reject traversal sequences
Caveat Minor version upgrade within pre-1.0 release; review release notes for any changes to API behavior

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

Have this fixed 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-2026-13426 in production — separate from our analysis above.

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What this is

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  • Version or environment caveats, and links to real fixes
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