Mattermost doesn't enforce administrator authorization on the {{setDefaultInstance}} call within the {{/gitlab connect}} command handler

Mattermost versions 11.7.x slash command.. Mattermost Advisory ID: MMSA-2026-00644...

GHSA-2G8V-GRQ3-HQ2G Mattermost doesn't enforce administrator authorization on the {{setDefaultInstance}} call within the {{/gitlab connect}} command handler

Mattermost versions 11.7.x slash command.. Mattermost Advisory ID: MMSA-2026-00644...

CVE-2026-5139

Mattermost versions 11.7.x slash command.. Mattermost Advisory ID: MMSA-2026-00644...

EUVD-2026-38246

Mattermost versions 11.7.x slash command.. Mattermost Advisory ID: MMSA-2026-00644...

CVE-2026-5139 GitLab Plugin Allows Non-Admin Users to Modify Default Instance Configuration

Mattermost versions 11.7.x slash command.. Mattermost Advisory ID: MMSA-2026-00644...

PT-2026-51304

Name of the Vulnerable Software and Affected Versions Mattermost version 11.7.0 Mattermost version 11.6.2 Mattermost version 11.5.5 Mattermost version 10.11.17 Description Improper authorization in the GitLab connect command handler allows any authenticated user to overwrite the global default...

CVE-2026-5139: Missing Authorization

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...