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...

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...

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...

PT-2026-91236

Name of the Vulnerable Software and Affected Versions Mattermost version 11.9.0 Mattermost version 11.8.4 Mattermost version 11.7.7 Description Authorization boundaries are not properly enforced on the access control policy update endpoint. This allows a channel or team administrator to detach a...

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...

CVE-2026-15754: Incorrect Authorization

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...