A improper authentication vulnerability exists in Rocket.Chat <v5, <v4.8.2 and <v4.7.5 that allowed two factor authentication can be bypassed when telling the server to use CAS during login.
Exploitability
AV:NAC:LPR:LUI:NScope
S:UImpact
C:HI:HA:H8.8/CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:HAuthentication