CVE-2026-6739 MEDIUM

CVE-2026-6739: Mattermost: Delegated admins could patch protected default system roles

Vendor Mattermost
Product Mattermost
Weakness CWE-863 · Incorrect authorization
Published June 12, 2026
Last update June 13, 2026
View on NVD All CVEs

CVSS base score

6.7/10
Attack vector Network
Attack complexity Low
Privileges required High
User interaction None
Confidentiality High
Integrity High

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:U/C:H/I:H/A:L

What the vulnerability does

01Description

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 system-level permission when patching protected default system roles, which allows authenticated users with delegated user-management permissions to escalate privileges by altering built-in role permissions via the role patch API.. Mattermost Advisory ID: MMSA-2026-00656

Key dates

02Disclosure timeline

June 12, 2026 CVE published
June 13, 2026 Record updated