CVE-2026-10080 PUBLISHED

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

Assigner: Mattermost
Reserved: 29.05.2026 Published: 17.08.2026 Updated: 17.08.2026

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

Metrics

CVSS 3.1

CVSS Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
CVSS Score: 6.5

Attack Vector	Network	Scope	Unchanged
Attack Complexity	Low	Confidentiality Impact	None
Privileges Required	Low	Integrity Impact	None
User Interaction	None	Availability Impact	High

CVSS 3.1

Product Status

Vendor	Mattermost
Product	Mattermost
Versions	Default: unaffected affected from 11.7.0 to 11.7.6 (incl.) affected from 10.11.0 to 10.11.21 (incl.) affected from 11.8.0 to 11.8.3 (incl.) Version 11.9.0 is unaffected Version 11.7.7 is unaffected Version 10.11.22 is unaffected Version 11.8.4 is unaffected

Solutions

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

Credits

alimursaliyev finder

References

MMSA-2026-00687

Problem Types

CWE-704: Incorrect Type Conversion or Cast CWE