Mattermost versions 10.5.x <= 10.5.7, 9.11.x <= 9.11.16 fail to negotiate a new token when accepting the invite which allows a user that intercepts both invite and password to send synchronization payloads to the server that originally created the invite via the REST API.
{
"unresolved_ranges": [
{
"source": "AFFECTED_FIELD",
"extracted_events": [
{
"introduced": "10.5.0"
},
{
"last_affected": "10.5.7"
},
{
"introduced": "9.11.0"
},
{
"last_affected": "9.11.16"
}
]
}
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2025/6xxx/CVE-2025-6227.json",
"cna_assigner": "Mattermost",
"cwe_ids": [
"CWE-522"
]
}