Vulnerability Details CVE-2026-5139
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
Exploit prediction scoring system (EPSS) score
EPSS Score 0.002
EPSS Ranking 6.5%
CVSS Severity
CVSS v3 Score 5.4
References