CVE-2026-10527CWE-863broken-access-control

CVE-2026-10527

Medium · published August 17, 2026

CVSS v3.1
6.3
EPSS
0%
Percentile
16.8
In the wild
Unconfirmed
What it is

Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fails to reconcile SchemeAdmin flags with a user's current role which allows a user demoted to System Guest to retain Board Admin privileges and perform admin-only operations via the Boards REST API or UI.. Mattermost Advisory ID: MMSA-2026-00691

The record
Technical detail
CVSS v3.1
6.3 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:L/I:L/A:L
CVSS v4.0
Not supplied
EPSS
0.00260 · 16.8th percentile
Weakness
CWE-863 · Incorrect Authorization
Published
2026-08-17T19:16Z
Affected products (3)
ProductVersionsFixed in
mattermost/mattermost_server≥ 10.11.0, < 10.11.2210.11.22
mattermost/mattermost_server≥ 11.7.0, < 11.7.711.7.7
mattermost/mattermost_server≥ 11.8.0, < 11.8.411.8.4
References (1)
https://mattermost.com/security-updates · [email protected]
EPSS history
Timeline
  • 17 AUG 14:37Z
    Boards plugin retains Board Admin rights for users demoted to System Guest
    cvelistv5