Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fail to validate that users have read access to a channel before linking a board to it, which allows an authenticated attacker to discover the membership of private channels on the same team via creating, patching, importing, or bulk-creating boards with an arbitrary channelId. Mattermost Advisory ID: MMSA-2026-00674
{
"cna_assigner": "Mattermost",
"cwe_ids": [
"CWE-862"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/16xxx/CVE-2026-16047.json",
"unresolved_ranges": [
{
"extracted_events": [
{
"introduced": "11.7.0"
},
{
"last_affected": "11.7.6"
},
{
"introduced": "10.11.0"
},
{
"last_affected": "10.11.21"
},
{
"introduced": "11.8.0"
},
{
"last_affected": "11.8.3"
}
],
"source": "AFFECTED_FIELD"
}
]
}{
"cpe": "cpe:2.3:a:mattermost:mattermost_server:*:*:*:*:*:*:*:*",
"extracted_events": [
{
"introduced": "10.11.0"
},
{
"fixed": "10.11.22"
},
{
"introduced": "11.7.0"
},
{
"fixed": "11.7.7"
},
{
"introduced": "11.8.0"
},
{
"fixed": "11.8.4"
}
],
"source": "CPE_RANGE"
}