CVE-2025-11777

Cross-team channel membership access

Published Nov 13, 2025 CVSS 3.1 · 3.1 Low EPSS < 1% KEV · Not listed
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

Remediation

Vendor Solution

Update Mattermost to versions 11.0.0, 10.11.4, 10.5.12 or higher.

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-mqcj-8c2g-h97q Mattermost Incorrect Authorization vulnerability
References
History
Type Values Removed Values Added
First Time appeared Mattermost mattermost Server
CPEs cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*
Vendors & Products Mattermost mattermost Server
Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost
Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}

Type Values Removed Values Added
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
Title Cross-team channel membership access
Weaknesses CWE-863
References
Metrics cvssV3_1

{'score': 3.1, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Mattermost
Published
Updated
Nov 13, 2025, 6:01 PM
Reserved
Oct 15, 2025, 11:37 AM
Status
Analyzed
Published
Nov 13, 2025, 6:15 PM
Modified
Oct 19, 2026, 1:10 PM