CVE-2026-13426Network attack vector

Authenticated API redirection via traversing path IDs

Published Jun 26, 2026 · Updated Jun 26, 2026

Path traversal in github.com/mattermost/mattermost/server/public before 0.1.22 allows remote authenticated users to redirect API calls. Client4 inserts attacker-controlled IDs containing traversal components into API route paths without validating or constraining those components, so requests can reach unintended endpoints. A valid low-privilege session is required, and redirected calls can expose or modify data available through unintended API endpoints without interrupting the service.

CVSS severity5.4
Medium
EPSS probability0.29%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Path traversal in github.com/mattermost/mattermost/server/public before 0.1.22 allows remote authenticated users to redirect API calls. Client4 inserts attacker-controlled IDs containing traversal components into API route paths without validating or constraining those components, so requests can reach unintended endpoints. A valid low-privilege session is required, and redirected calls can expose or modify data available through unintended API endpoints without interrupting the service.

The record

CVE
CVE-2026-13426
Published
Jun 26, 2026
Updated
Jun 26, 2026
Vendor
Mattermost
Product
github.com/mattermost/mattermost/server/public
Classifications
CWE-22
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Jun 26, 2026CVE publishedPublication date reported by the CVE source.
  2. Jun 26, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=v0.0.0 <v0.1.22

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

Mattermost · github.com/mattermost/mattermost/server/publicversion=v0.0.0 <v0.1.22

Published CVSS scores

5.4Mattermost, Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 9, 2026Sep 15, 2026
Latest reporting daySep 15, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-22Improper Limitation of a Pathname to a Restricted Directory ('Path Traversal')

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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