CVE-2026-82920CWE-863broken-access-control

CVE-2026-82920

Medium · published September 14, 2026

CVSS v3.1
5.5
EPSS
0%
Percentile
16.1
In the wild
Unconfirmed
What it is

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

The record
Technical detail
CVSS v3.1
5.5 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:L/I:L/A:N
CVSS v4.0
Not supplied
EPSS
0.00255 · 16.1th percentile
Weakness
CWE-863 · Incorrect Authorization
Published
2026-09-14T18:17Z
Affected products (3)
ProductVersionsFixed in
mattermost/mattermost_server≥ 11.7.0, < 11.7.811.7.8
mattermost/mattermost_server≥ 11.8.0, < 11.8.511.8.5
mattermost/mattermost_server≥ 11.9.0, < 11.9.111.9.1
References (1)
https://mattermost.com/security-updates · [email protected]
EPSS history
Timeline
  • 17 SEP 03:33Z
    EPSS moved — → 0%
    epss
  • 14 SEP 13:59Z
    Mattermost ABAC parent policy bypass via policy update endpoint
    cvelistv5