CVE-2026-82920

Mattermost versions 11.9.x = 11.9.0, 11.8.x = 11.8.4, 11.7.x = 11.7.7 fail to enforce authorization boundaries on the access control policy update endpoint which allows a channel or team administrator to detach a system-assigned ABAC parent policy via a crafted PUT /api/v4/accesscontrolpolicies...

CVE-2026-82920

Mattermost versions 11.9.x ≤ 11.9.0 , 11.8.x ≤ 11.8.4 , and 11.7.x ≤ 11.7.7 fail to enforce authorization boundaries on the ABAC policy update endpoint. A channel or team administrator can detach a system-assigned ABAC parent policy by sending a crafted PUT /api/v4/access_control_policies request...

EUVD-2026-77487

Mattermost versions 11.9.x = 11.9.0, 11.8.x = 11.8.4, 11.7.x = 11.7.7 fail to enforce authorization boundaries on the access control policy update endpoint which allows a channel or team administrator to detach a system-assigned ABAC parent policy via a crafted PUT /api/v4/accesscontrolpolicies...

PT-2026-91236

Mattermost versions 11.9.x = 11.9.0, 11.8.x = 11.8.4, 11.7.x = 11.7.7 fail to enforce authorization boundaries on the access control policy update endpoint which allows a channel or team administrator to detach a system-assigned ABAC parent policy via a crafted PUT /api/v4/access control policies...

CVE-2026-82920: Incorrect Authorization

Mattermost versions 11.9.x = 11.9.0, 11.8.x = 11.8.4, 11.7.x = 11.7.7 fail to enforce authorization boundaries on the access control policy update endpoint which allows a channel or team administrator to detach a system-assigned ABAC parent policy via a crafted PUT /api/v4/accesscontrolpolicies...

Mattermost Server 11.7.x < 11.7.7 / 11.8.x < 11.8.4 Incorrect Authorization (MMSA-2026-00718)

The version of Mattermost Server installed on the remote host is affected by a vulnerability as referenced in the MMSA-2026-00718 advisory. - Mattermost versions 11.7.x = 11.7.6, 11.8.x = 11.8.3 The access control policy unassign endpoint fails to re-validate that each target channel still belong...

CVE-2026-15754

Mattermost versions 11.7.x = 11.7.6, 11.8.x = 11.8.3 The access control policy unassign endpoint fails to re-validate that each target channel still belongs to the requesting admin's team, which allows an authenticated team administrator to remove ABAC attribute-based access control policy...

PT-2026-76668

Mattermost versions 11.7.x = 11.7.6, 11.8.x = 11.8.3 The access control policy unassign endpoint fails to re-validate that each target channel still belongs to the requesting admin's team, which allows an authenticated team administrator to remove ABAC attribute-based access control policy...