CVE-2026-3115

Published: Mar 26, 2026Modified: Jun 17, 2026

4.3

Vector

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

Exploitability: 2.8 / Impact: 1.4

Source: responsibledisclosure@mattermost.com (Secondary)

Description

Mattermost versions 11.2.x <= 11.2.2, 10.11.x <= 10.11.10, 11.4.x <= 11.4.0, 11.3.x <= 11.3.1 fail to apply view restrictions when retrieving group member IDs, which allows authenticated guest users to enumerate user IDs outside their allowed visibility scope via the group retrieval endpoint.. Mattermost Advisory ID: MMSA-2026-00594

Affected (4)

Products: Mattermost: Mattermost Server

Mattermost

1 product

Mattermost Server

Configuration A

4 vulnerable

Vulnerable Software	Affected Versions
Mattermost Mattermost Server	From 10.11.0 to 10.11.11
Mattermost Mattermost Server	From 11.2.0 to 11.2.3
Mattermost Mattermost Server	From 11.3.0 to 11.3.2
Mattermost Mattermost Server	Version 11.4.0

Related CWEs

CWE-863

Incorrect Authorization

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. This allows attackers to bypass intended access restrictions.

References (1)

https://mattermost.com/security-updates

Source: responsibledisclosure@mattermost.com

Vendor Advisory

Timeline

No history available yet.