# CVE-2026-82920

## Summary

- **CVE ID:** CVE-2026-82920
- **Severity:** MEDIUM
- **CVSS Score:** 5.5 (CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N)
- **CWE:** CWE-863
- **Published:** Sep 14, 2026
- **Last Modified:** Sep 14, 2026

## Description

Mattermost versions 11.9.x <= 11.9.0, 11.8.x <= 11.8.4, 11.7.x <= 11.7.7 fail to enforce authorization boundaries on the access control policy update endpoint which allows a channel or team administrator to detach a system-assigned ABAC parent policy via a crafted PUT /api/v4/access_control_policies request with an empty imports list.. Mattermost Advisory ID: MMSA-2026-00724

## Affected Products

- Mattermost — Mattermost (11.9.0)
- Mattermost — Mattermost (11.8.0)
- Mattermost — Mattermost (11.7.0)
- Mattermost — Mattermost (11.10.0)
- Mattermost — Mattermost (11.9.1)
- Mattermost — Mattermost (11.8.5)
- Mattermost — Mattermost (11.7.8)

## References

- [CNA](https://mattermost.com/security-updates)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.15%
- **EPSS Percentile:** 4.8

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_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-17._