Mattermost Desktop App versions <=6.2 6.2.2.0 fails to validate the IPC sender in the leaveCall handler which allows a malicious or compromised Mattermost server (or a user with script access to a connected server view) to disconnect an active call belonging to a different connected server via the desktopAPI.leaveCall IPC message. Mattermost Advisory ID: MMSA-2026-00699
{
"cna_assigner": "Mattermost",
"cwe_ids": [
"CWE-346"
],
"osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/12xxx/CVE-2026-12284.json",
"unresolved_ranges": [
{
"extracted_events": [
{
"last_affected": "6.2.2"
}
],
"source": "AFFECTED_FIELD"
}
]
}