CVE-2026-15754
published 2026-08-17CVE-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…
PriorityP422medium4.2CVSS 3.1
AVNACHPRHUIRSUCNIHAN
EPSS
0.25%
14.9th percentile
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
4 ranges
| Vendor | Product | Version range | Fixed in |
|---|---|---|---|
| mattermost | mattermost | 11.7.0 – 11.7.6 | — |
| mattermost | mattermost | 11.8.0 – 11.8.3 | — |
| mattermost | mattermost_server | >= 11.7.0 < 11.7.7 | 11.7.7 |
| mattermost | mattermost_server | >= 11.8.0 < 11.8.4 | 11.8.4 |
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VulDB
Mattermost up to 11.7.6/11.8.3 Policy Unassign API access control (Nessus ID 338330)
vuldb·2026-08-21·CVSS 4.2
CVE-2026-15754 [MEDIUM] Mattermost up to 11.7.6/11.8.3 Policy Unassign API access control (Nessus ID 338330)
A vulnerability labeled as problematic has been found in Mattermost up to 11.7.6/11.8.3. This issue affects some unknown processing of the component Policy Unassign API. The manipulation results in improper access controls.
This vulnerability is identified as CVE-2026-15754. The attack can be executed remotely. There is not any exploit available.
The affected component should be upgraded.
GHSA
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 all
ghsa_unreviewed·2026-08-17
CVE-2026-15754 [MEDIUM] CWE-863 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 all
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
No detection rules found.
No public exploits indexed.
No writeups or analysis indexed.
2026-08-17
Published