# CVE-2026-15754: Missing per-channel team-scope check in ABAC access control policy unassign allows cross-team policy removal

> CVE-2026-15754: Missing per-channel team-scope check in ABAC access control policy unassign allows cross-team policy removal. CVSS 4.2 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-15754
Last updated: 2026-08-18T20:24:58Z

- Published: 2026-08-17 14:36 UTC · Updated: 2026-08-18 20:24 UTC · Assigner: Mattermost
- CVSS: 4.2 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:H/PR:H/UI:R/S:U/C:N/I:H/A:N
- EPSS: 0.25%, 16th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-863

## 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 vendors and products

- Mattermost: Mattermost

## Tracked companies

- [Mattermost](https://rewindex.com/company/mattermost.md)

## References

- [CVE record on cve.org](https://www.cve.org/CVERecord?id=CVE-2026-15754)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-15754)
- [https://mattermost.com/security-updates](https://mattermost.com/security-updates)

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_Sources: CVE records from the CVE Program (cve.org). CVE® is a registered trademark of The MITRE Corporation. (https://www.cve.org/) This product uses data from the NVD API but is not endorsed or certified by the NVD. (https://nvd.nist.gov/) Known Exploited Vulnerabilities catalog from CISA. (https://www.cisa.gov/known-exploited-vulnerabilities-catalog) EPSS scores from FIRST (Exploit Prediction Scoring System). (https://www.first.org/epss/)_


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Canonical: https://rewindex.com/cve/CVE-2026-15754 · Markdown: https://rewindex.com/cve/CVE-2026-15754.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-15754 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:11:37.152Z