CVE-2026-5139

EUVD-2026-38246
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
ProviderTypeBase ScoreAtk. VectorAtk. ComplexityPriv. RequiredVector
MattermostCNA
5.4 MEDIUM
NETWORK
LOW
LOW
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/A:L
Base Score
CVSS 3.x
EPSS Score
Percentile: 20.89%
Affected Products (NVD)
VendorProductVersion
mattermostmattermost_server
10.11.0 ≤
𝑥
< 10.11.18
mattermostmattermost_server
11.5.0 ≤
𝑥
< 11.5.6
mattermostmattermost_server
11.6.0 ≤
𝑥
< 11.6.3
mattermostmattermost_server
11.7.0 ≤
𝑥
< 11.7.1
𝑥
= Vulnerable software versions
Early Detection
Affected products identified ahead of NVD analysis through intelligence sources.
VendorProductVersionSource
mattermostmattermost
𝑥
≤ 11.7.0
CNA
mattermostmattermost
11.6.0 ≤
𝑥
≤ 11.6.2
CNA
mattermostmattermost
11.5.0 ≤
𝑥
≤ 11.5.5
CNA
mattermostmattermost
10.11.0 ≤
𝑥
≤ 10.11.17
CNA