Mattermost · Mattermost · CVE-2026-5139
**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 GitLab instance configuration. This occurs because the software fails to enforce administrator authorization on the `setDefaultInstance` function call when using the '/gitlab connect <instance-name>' slash command.
**Recommendations**
At the moment, there is no information about a newer version that contains a fix for this vulnerability.