CVE-2026-10080

Boards plugin panics on WebSocket command with non-string field types

Published Aug 17, 2026 CVSS 3.1 · 6.5 Medium EPSS < 1% KEV · Not listed
Description
Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fails to validate WebSocket command field types which allows an authenticated user to crash the plugin process and deny service to all Boards users via a custom_focalboard_SUBSCRIBE_TEAM message with a non-string teamId.. Mattermost Advisory ID: MMSA-2026-00687

Remediation

Vendor Solution

Update Mattermost to versions 11.9.0, 11.7.7, 10.11.22, 11.8.4 or higher.

Tracking

Sign in to view the affected projects.

Advisories

No advisories available
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
Metrics ssvc

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

Type Values Removed Values Added
First Time appeared Mattermost
Mattermost mattermost
Vendors & Products Mattermost
Mattermost mattermost
Type Values Removed Values Added
Description Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fails to validate WebSocket command field types which allows an authenticated user to crash the plugin process and deny service to all Boards users via a custom_focalboard_SUBSCRIBE_TEAM message with a non-string teamId.. Mattermost Advisory ID: MMSA-2026-00687
Title Boards plugin panics on WebSocket command with non-string field types
Weaknesses CWE-704
References
Metrics cvssV3_1

{'score': 6.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H'}

Weaknesses

Sources

Status
PUBLISHED
Assigner
Mattermost
Published
Updated
Aug 18, 2026, 3:23 PM
Reserved
May 29, 2026, 10:40 AM
Status
Analyzed
Published
Aug 17, 2026, 10:16 PM
Modified
Aug 18, 2026, 4:19 PM