Description
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 assignments from channels outside their team via the policy unassign API after a channel has been moved to another team.. Mattermost Advisory ID: MMSA-2026-00718
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Mattermost | Mattermost | 11.7.0 – ≤ 11.7.6, 11.8.0 – ≤ 11.8.3 | 11.9.0 |
Advisories 2
- NCSC-2026-0305 Kwetsbaarheden verholpen in Mattermost NCSC-NL (Netherlands) · Aug 19, 2026
- WID-SEC-2026-2411 Mattermost: Mehrere Schwachstellen ermöglichen nicht spezifizierten Angriff BSI CERT-Bund (WID) · Aug 17, 2026
References
- MMSA-2026-00718 vendor-advisory