CVE-2025-10545

Guest user can add unauthorized team users to private channels

Published Oct 16, 2025 CVSS 3.1 · 3.1 Low EPSS < 1% KEV · Not listed
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

Remediation

Vendor Solution

Update Mattermost to versions 10.12.0, 10.5.11, 10.11.3 or higher.

Tracking

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Advisories

Source ID Title
Github GHSA Github GHSA GHSA-424h-xj87-m937 Mattermost has an 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 10.5.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
Title Guest user can add unauthorized team users to private channels
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
Oct 16, 2025, 2:14 PM
Reserved
Sep 16, 2025, 8:41 AM
Status
Analyzed
Published
Oct 16, 2025, 9:15 AM
Modified
Oct 19, 2026, 4:10 PM