Is CVE-2026-15754 being exploited?

No public exploit is currently tracked.

How severe is CVE-2026-15754?

CVE-2026-15754 has a CVSS v3 severity of MEDIUM (4.2).

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CVE-2026-15754

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