GHSA-2g8v-grq3-hq2gMediumCVSS 5.4

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

Published
June 22, 2026
Last Modified
September 15, 2026

🔗 CVE IDs covered (1)

CVE-2026-5139 →

📋 Description

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 }} slash command.. Mattermost Advisory ID: MMSA-2026-00644

🎯 Affected products4

  • go/github.com/mattermost/mattermost-server:>= 11.7.0, < 11.7.1
  • go/github.com/mattermost/mattermost-server:>= 11.6.0, < 11.6.3
  • go/github.com/mattermost/mattermost-server:>= 11.5.0, < 11.5.6
  • go/github.com/mattermost/mattermost-server:>= 10.11.0, < 10.11.18

🔗 References (3)