EUVD-2026-77371

Mattermost versions 11.9.x = 11.9.0, 11.8.x = 11.8.4, 11.7.x = 11.7.7, 10.11.x = 10.11.22 fail to validate channel member-management permission during playbook run creation, allowing an authenticated channel member to add an arbitrary user to a restricted channel via the run owner field...

CVE-2026-4055

Mattermost CVE-2026-4055 affects Mattermost versions 11.5.x

CVE-2026-26304

Mattermost vulnerability CVE-2026-26304 affects Mattermost server versions 11.3.x (up to 11.3.0) and 11.2.x (up to 11.2.2). The issue is a permission check bypass in the playbook run creation path: run_create permission for an empty playbookId is not verified, enabling team members to create unau...