Mattermost fails to perform proper authorization in the /plugins/focalboard/api/v2/users endpoint allowing an attacker who is a guest user and knows the ID of another user to get their information (e.g. name, surname, nickname) via Mattermost Boards.
{
"versions": [
{
"introduced": "0"
},
{
"last_affected": "7.8.12"
},
{
"introduced": "8.0.0"
},
{
"last_affected": "8.1.3"
}
]
}