CVE-2026-10080

Name of the Vulnerable Software and Affected Versions Mattermost versions 11.7.0 through 11.7.6 Mattermost versions 10.11.0 through 10.11.21 Mattermost versions 11.8.0 through 11.8.3

Description An issue exists where the software fails to validate WebSocket command field types. This allows an authenticated user to crash the plugin process, resulting in a denial of service for all Boards users. The flaw is triggered by sending a custom focalboard SUBSCRIBE TEAM message containing a non-string teamId variable.

Recommendations Update Mattermost versions 11.7.0 through 11.7.6 to a version newer than 11.7.6. Update Mattermost versions 10.11.0 through 10.11.21 to a version newer than 10.11.21. Update Mattermost versions 11.8.0 through 11.8.3 to a version newer than 11.8.3.