Mattermost Server 10.11.x < 10.11.22 / 11.7.x < 11.7.7 Multiple Vulnerabilities (MMSA-2026-00672, MMSA-2026-00675, MMSA-2026-00704)

The version of Mattermost Server installed on the remote host is affected by multiple vulnerabilities as referenced in the MMSA-2026-00672, MMSA-2026-00675, MMSA-2026-00704 advisories. - Mattermost versions 11.7.x = 11.7.6, 10.11.x = 10.11.21 fail to prevent guest users from receiving Board Admin...

CVE-2026-4055 Insufficient permission validation on cross-team playbook run creation

Mattermost versions 11.5.x = 11.5.1 fail to validate team-level runcreate permission against the target team when creating a playbook run which allows an authenticated team member to create runs in teams where they lack permission via specifying a different team ID in the run creation API request...

CVE-2026-26304 Permission Bypass in Playbook Run Creation

Mattermost versions 11.3.x = 11.3.0, 11.2.x = 11.2.2 fail to verify runcreate permission for empty playbookId, which allows team members to create unauthorized runs via the playbook run API. Mattermost Advisory ID: MMSA-2025-00542...

CVE-2026-26304 Permission Bypass in Playbook Run Creation

Mattermost versions 11.3.x = 11.3.0, 11.2.x = 11.2.2 fail to verify runcreate permission for empty playbookId, which allows team members to create unauthorized runs via the playbook run API. Mattermost Advisory ID: MMSA-2025-00542...