Mattermost versions 10.12.x <= 10.12.1, 10.11.x <= 10.11.4, 10.5.x <= 10.5.12, 11.0.x <= 11.0.3 fail to properly validate OAuth state tokens during OpenID Connect authentication which allows an authenticated attacker with team creation privileges to take over a user account via manipulation of authentication data during the OAuth completion flow. This requires email verification to be disabled (default: disabled), OAuth/OpenID Connect to be enabled, and the attacker to control two users in the SSO system with one of them never having logged into Mattermost.
{
"versions": [
{
"introduced": "10.5.0"
},
{
"fixed": "10.5.13"
},
{
"introduced": "10.11.0"
},
{
"fixed": "10.11.5"
},
{
"introduced": "10.12.0"
},
{
"fixed": "10.12.2"
},
{
"introduced": "11.0.0"
},
{
"fixed": "11.0.4"
}
]
}