CVE-2026-7387
Received Received - Intake
Privilege Escalation in Mattermost via Group Sync API

Publication date: 2026-06-12

Last updated on: 2026-06-12

Assigner: Mattermost, Inc.

Description
Mattermost versions 11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, 10.11.x <= 10.11.16 Mattermost fails to require role-management authorization when setting the scheme_admin flag on group syncable link and patch endpoints, which allows a user with group-link permissions to escalate themselves and group members to team or channel admin via crafted API requests.. Mattermost Advisory ID: MMSA-2026-00665
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Meta Information
Published
2026-06-12
Last Modified
2026-06-12
Generated
2026-06-12
AI Q&A
2026-06-12
EPSS Evaluated
N/A
NVD
CVE-2026-7387
EUVD
EUVD-2026-36503
Affected Vendors & Products
Showing 4 associated CPEs
Vendor Product Version / Range
mattermost mattermost to 11.6.1 (inc)
mattermost mattermost to 11.5.4 (inc)
mattermost mattermost to 10.11.15 (inc)
mattermost mattermost to 10.11.16 (inc)
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Exploitability
CWE
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KEV
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CWE ID Description
CWE-863 The product performs an authorization check when an actor attempts to access a resource or perform an action, but it does not correctly perform the check.
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Executive Summary

This vulnerability exists in Mattermost versions 11.6.x up to 11.6.1, 11.5.x up to 11.5.4, and 10.11.x up to 10.11.16. It occurs because Mattermost does not require proper role-management authorization when setting the scheme_admin flag on group syncable link and patch endpoints.

As a result, a user who has group-link permissions can exploit this flaw by crafting specific API requests to escalate their own privileges and those of group members to team or channel admin.

Impact Analysis

This vulnerability can have a significant impact because it allows unauthorized privilege escalation.

  • An attacker with group-link permissions can elevate themselves and other group members to team or channel administrators.
  • This can lead to unauthorized access to sensitive information, modification of team or channel settings, and potential disruption of normal operations.
  • Given the CVSS base score of 8.8, the vulnerability is considered high severity, affecting confidentiality, integrity, and availability.
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