An issue was discovered in Mattermost Server before 4.2.0, 4.1.1, and 4.0.5, when used as an OAuth 2.0 service provider. Sometimes. resource-owner authorization is bypassed, allowing account takeover.
Exploitability
AV:NAC:LPR:LUI:NScope
S:UImpact
C:HI:HA:N8.1/CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N