# CVE-2026-82920: Mattermost ABAC parent policy bypass via policy update endpoint

> CVE-2026-82920: Mattermost ABAC parent policy bypass via policy update endpoint. CVSS 5.5 (CVSS 3.1).

Canonical: https://rewindex.com/cve/CVE-2026-82920
Last updated: 2026-10-07T18:04:00Z

- Published: 2026-09-14 13:59 UTC · Updated: 2026-10-07 18:04 UTC · Assigner: Mattermost
- CVSS: 5.5 (CVSS 3.1) · Severity: Medium · Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N
- EPSS: 0.26%, 17th percentile (scored 2026-10-25)
- CISA KEV: no
- CWE: CWE-863

## 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 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-2026-82920)
- [NVD entry](https://nvd.nist.gov/vuln/detail/CVE-2026-82920)
- [https://mattermost.com/security-updates](https://mattermost.com/security-updates)

---

_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/)_


---
Canonical: https://rewindex.com/cve/CVE-2026-82920 · Markdown: https://rewindex.com/cve/CVE-2026-82920.md · JSON: https://rewindex.com/api/v1/cves/CVE-2026-82920 · Data licensed CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/) · Generated 2026-10-26T03:12:52.572Z