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 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

Published 17 Aug 2026, 15:16 UTC Last modified 17 Aug 2026, 15:16 UTC

4.2

CVSS 3.1 MEDIUM base score CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:H/A:N

Attack profile

The conditions required to exploit this vulnerability and its potential impact.

Attack vector Network

Attack complexity High

Privileges required High

User interaction Required

Scope Unchanged

Confidentiality None

Integrity High

Availability None

Exploitability0.5

Impact3.6

Affected products

Product applicability statements supplied with the NVD record.

NVD has not published structured affected-product data for this record.

Weakness classification

CWE categories help security teams group the underlying software weakness.

CWECWE-863

Source references

External advisories, patches and technical reports attached to this CVE record.

NVD National Vulnerability Database recordnvd.nist.gov 01 Technical reference responsibledisclosure@mattermost.com