Mattermost versions 11.7.x <= 11.7.6, 10.11.x <= 10.11.21, 11.8.x <= 11.8.3 fails to validate WebSocket command field types which allows an authenticated user to crash the plugin process and deny service to all Boards users via a custom_focalboard_SUBSCRIBE_TEAM message with a non-string teamId.. Mattermost Advisory ID: MMSA-2026-00687
{
"cna_assigner": "Mattermost",
"cwe_ids": [
"CWE-704"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/10xxx/CVE-2026-10080.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"
}