CVE-2026-82920

Mattermost ABAC parent policy bypass via policy update endpoint

State: Published
Severity: 5.5 Medium
Published: Sep 14, 2026
Updated: Sep 14, 2026
Reserved: Aug 31, 2026

Description

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 request with an empty imports list.. Mattermost Advisory ID: MMSA-2026-00724

Scores

CVSS	Score	Vector	Source
3.1	5.5 Medium	CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N	Mattermost

Weaknesses

CWE-863 Incorrect Authorization

Affected Products

Product	Versions
MattermostMattermost	11.9.0 through 11.9.0Affected 11.8.0 through 11.8.4Affected 11.7.0 through 11.7.7Affected 11.10.0Not affected 11.9.1Not affected 11.8.5Not affected 11.7.8Not affected

References

MMSA-2026-00724vendor-advisory

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