CVE-2026-8821

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-2026-8821 Playbooks run owner channel membership permission bypass

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...

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-2026-8821 Playbooks run owner channel membership permission bypass

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...

PT-2026-91154

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-2026-8821: Missing Authorization

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...

Mattermost Server 10.11.x < 10.11.17 / 11.5.x < 11.5.5 / 11.6.x < 11.6.2 Improper Authorization (MMSA-2026-00629)

The version of Mattermost Server installed on the remote host is affected by a vulnerability as referenced in the MMSA-2026-00629 advisory. - Mattermost Server fails to validate team-level runcreate permission against the target team when creating a playbook run which allows an authenticated team...

CVE-2026-4055

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

CVE-2026-4055: Incorrect Authorization

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...

SUSE CVE-2026-26304

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

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...

Incorrect Authorization

Overview Affected versions of this package are vulnerable to Incorrect Authorization via the playbook run API when the runcreate permission is not verified for an empty playbookId. An attacker can initiate unauthorized playbook runs by sending crafted API requests. Remediation Upgrade...

Mattermost fails to verify run_create permission for empty playbookId

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...

EUVD-2026-12512

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...

GHSA-4PMX-622H-X359 Mattermost fails to verify run_create permission for empty playbookId

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

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...

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...

CVE-2026-26304: Incorrect Authorization

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...

GHSA-F556-49JC-4RVC Ansible does not collect garbage after playbook run

A flaw was found in Ansible Base when using the awsssm connection plugin as its garbage collector is not happening after the playbook run is completed. Files would remain in the bucket exposing the data. This issue directly affects data confidentiality...