CVE-2026-5139CWE-862

GitLab Plugin Allows Non-Admin Users to Modify Default Instance Configuration

Medium · published June 22, 2026

CVSS v3.1
5.4
EPSS
0%
Percentile
20.1
In the wild
Unconfirmed
What it is

Mattermost versions 11.7.x <= 11.7.0, 11.6.x <= 11.6.2, 11.5.x <= 11.5.5, 10.11.x <= 10.11.17 fail to enforce administrator authorization on the {{setDefaultInstance}} call within the {{/gitlab connect}} command handler, which allows any authenticated user to overwrite the global default GitLab instance configuration via the {{/gitlab connect <instance-name>}} slash command.. Mattermost Advisory ID: MMSA-2026-00644

The record
Technical detail
CVSS v3.1
5.4 · MEDIUM
Vector
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
CVSS v4.0
Not supplied
EPSS
0.00287 · 20.1th percentile
Weakness
CWE-862 · Missing Authorization
Published
2026-06-22T13:34Z
EPSS history
Timeline
  • 22 JUN 13:34Z
    GitLab Plugin Allows Non-Admin Users to Modify Default Instance Configuration
    cvelistv5