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
{
"cwe_ids": [
"CWE-862"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/5xxx/CVE-2026-5139.json",
"cna_assigner": "Mattermost",
"unresolved_ranges": [
{
"extracted_events": [
{
"introduced": "11.7.0"
},
{
"last_affected": "11.7.0"
},
{
"introduced": "11.6.0"
},
{
"last_affected": "11.6.2"
},
{
"introduced": "11.5.0"
},
{
"last_affected": "11.5.5"
},
{
"introduced": "10.11.0"
},
{
"last_affected": "10.11.17"
}
],
"source": "AFFECTED_FIELD"
}
]
}{
"cpe": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
"extracted_events": [
{
"introduced": "10.11.0"
},
{
"fixed": "10.11.18"
},
{
"introduced": "11.5.0"
},
{
"fixed": "11.5.6"
},
{
"introduced": "11.6.0"
},
{
"fixed": "11.6.3"
},
{
"introduced": "11.7.0"
},
{
"fixed": "11.7.1"
}
],
"source": "CPE_RANGE"
}