---
id: CVE-2026-7387
aliases:
  - GHSA-6hxm-w4hv-vgvw
title: >-
  Mattermost doesn't require role-management authorization when setting the
  scheme_admin flag on group syncable link and patch endpoints
summary: >-
  Mattermost doesn't require role-management authorization when setting the
  scheme_admin flag on group syncable link and patch endpoints
severity: high
cvss: 8.8
cvssVector: 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'
vendor: mattermost
product: github.com/mattermost/mattermost-server
ecosystem: go
affected:
  - 'github.com/mattermost/mattermost-server >= 11.6.0, < 11.6.1'
  - 'github.com/mattermost/mattermost-server >= 11.5.0, < 11.5.5'
  - 'github.com/mattermost/mattermost-server >= 10.11.0, < 10.11.17'
  - >-
    github.com/mattermost/mattermost/server/v8 >=
    8.0.0-20250731163400-5b955468ea1e, < 8.0.0-20260506065351-202d125afa87
patched:
  - github.com/mattermost/mattermost-server 11.6.1
  - github.com/mattermost/mattermost-server 11.5.5
  - github.com/mattermost/mattermost-server 10.11.17
  - github.com/mattermost/mattermost/server/v8 8.0.0-20260506065351-202d125afa87
published: '2026-06-12'
updated: '2026-08-25'
source: OSV
sourceUrl: 'https://osv.dev/vulnerability/GHSA-6hxm-w4hv-vgvw'
references:
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-7387'
  - url: 'https://github.com/mattermost/mattermost/pull/36434'
  - url: 'https://github.com/mattermost/mattermost/pull/36432'
  - url: 'https://github.com/mattermost/mattermost/pull/36431'
  - url: 'https://github.com/mattermost/mattermost/pull/36423'
  - url: 'https://github.com/mattermost/mattermost/pull/36316'
  - url: >-
      https://github.com/mattermost/mattermost/commit/d5f29c8ebbeb04460d16d9e2635ce50deeb78428
  - url: >-
      https://github.com/mattermost/mattermost/commit/a9e574a82633915f22071f0d7ca2b006f249ec2a
  - url: >-
      https://github.com/mattermost/mattermost/commit/8c72083414e675c97987374395e36d1f36b4bd8a
  - url: >-
      https://github.com/mattermost/mattermost/commit/202d125afa87fe39611686850fd82590c99ca344
  - url: >-
      https://github.com/mattermost/mattermost/commit/1ce2484a00c9821ee19708d2c46720e4855033a9
  - url: 'https://github.com/mattermost/mattermost/releases/tag/v10.11.16'
  - url: 'https://github.com/mattermost/mattermost/releases/tag/v11.5.5'
  - url: 'https://github.com/mattermost/mattermost/releases/tag/v11.6.2'
  - url: 'https://github.com/mattermost/mattermost/releases/tag/v11.7.0'
  - url: 'https://mattermost.com/security-updates'
  - url: 'https://github.com/mattermost/mattermost'
tags:
  - osv
  - go
epss: 0.0031
epssPercentile: 0.24028
ingestedAt: '2026-08-25T19:26:22.895Z'
---

## Overview

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 fail 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

## Affected packages

- `github.com/mattermost/mattermost-server >= 11.6.0, < 11.6.1`
- `github.com/mattermost/mattermost-server >= 11.5.0, < 11.5.5`
- `github.com/mattermost/mattermost-server >= 10.11.0, < 10.11.17`
- `github.com/mattermost/mattermost/server/v8 >= 8.0.0-20250731163400-5b955468ea1e, < 8.0.0-20260506065351-202d125afa87`

## Remediation

Upgrade to a patched release:

- `github.com/mattermost/mattermost-server 11.6.1`
- `github.com/mattermost/mattermost-server 11.5.5`
- `github.com/mattermost/mattermost-server 10.11.17`
- `github.com/mattermost/mattermost/server/v8 8.0.0-20260506065351-202d125afa87`