BaseFortify

Publication date: 2025-10-16

Last updated on: 2025-10-21

Assigner: Mattermost, Inc.

Description

Mattermost versions 10.5.x <= 10.5.10, 10.11.x <= 10.11.2 fail to properly validate guest user permissions when adding channel members which allows guest users to add any team members to their private channels via the `/api/v4/channels/{channel_id}/members` endpoint

CVSS Scores

EPSS Scores

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Meta Information

Published

2025-10-16

Last Modified

2025-10-21

Generated

2026-07-06

AI Q&A

2025-10-16

EPSS Evaluated

2026-07-05

NVD

CVE-2025-10545

EUVD

EUVD-2025-34728

Affected Vendors & Products

Vendor	Product	Version / Range
mattermost	mattermost_server	From 10.5.0 (inc) to 10.5.11 (exc)
mattermost	mattermost_server	From 10.11.0 (inc) to 10.11.3 (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 Mattermost versions 10.5.x up to 10.5.10 and 10.11.x up to 10.11.2, where guest users are not properly validated when adding members to channels. Specifically, guest users can add any team members to their private channels by exploiting the /api/v4/channels/{channel_id}/members endpoint, which should restrict such actions.

Impact Analysis

The vulnerability allows guest users to add any team members to their private channels, potentially exposing private communication channels to unauthorized users. This could lead to unauthorized access to sensitive information shared within private channels.

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