CVE-2026-6739

Analyzed Analyzed - Analysis Complete

Privilege Escalation in Mattermost via Role Patch API

Publication date: 2026-06-12

Last updated on: 2026-06-18

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 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

CVSS Scores

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Meta Information

Published

2026-06-12

Last Modified

2026-06-18

Generated

2026-07-03

AI Q&A

2026-06-12

EPSS Evaluated

2026-07-01

NVD

CVE-2026-6739

EUVD

EUVD-2026-36499

Affected Vendors & Products

Vendor	Product	Version / Range
mattermost	mattermost_server	From 10.11.0 (inc) to 10.11.17 (exc)
mattermost	mattermost_server	From 11.5.0 (inc) to 11.5.5 (exc)
mattermost	mattermost_server	From 11.6.0 (inc) to 11.6.2 (exc)

Helpful Resources

Exploitability

CWE

KEV

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.

Attack-Flow Graph

Executive Summary

This vulnerability exists in certain versions of Mattermost (11.6.x <= 11.6.1, 11.5.x <= 11.5.4, 10.11.x <= 10.11.15, and 10.11.x <= 10.11.16) where the system fails to require system-level permission when patching protected default system roles.

As a result, authenticated users who have delegated user-management permissions can escalate their privileges by altering built-in role permissions through the role patch API.

Impact Analysis

This vulnerability allows users with certain delegated permissions to escalate their privileges beyond what is intended by modifying built-in role permissions.

Such privilege escalation can lead to unauthorized access to sensitive information or administrative functions, potentially compromising the confidentiality and integrity of the system.

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