BaseFortify

Publication date: 2025-11-13

Last updated on: 2025-11-17

Assigner: Mattermost, Inc.

Description

Mattermost versions 10.11.x <= 10.11.3, 10.5.x <= 10.5.11 fail to properly validate team membership permissions in the Add Channel Member API which allows users from one team to access user metadata and channel membership information from other teams via the API endpoint

CVSS Scores

EPSS Scores

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Meta Information

Published

2025-11-13

Last Modified

2025-11-17

Generated

2026-07-06

AI Q&A

2025-11-13

EPSS Evaluated

2026-07-05

NVD

CVE-2025-11777

Affected Vendors & Products

Vendor	Product	Version / Range
mattermost	mattermost_server	From 10.5.0 (inc) to 10.5.12 (exc)
mattermost	mattermost_server	From 10.11.0 (inc) to 10.11.4 (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 in Mattermost versions 10.11.x <= 10.11.3 and 10.5.x <= 10.5.11 involves improper validation of team membership permissions in the Add Channel Member API. It allows users from one team to access user metadata and channel membership information from other teams through the API endpoint.

Impact Analysis

The vulnerability can lead to unauthorized access where users from one team can view user metadata and channel membership details of other teams, potentially exposing sensitive information and violating privacy boundaries within the Mattermost platform.

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