In CAB approvals criteria, if one member of CAB approves the ticket then the tickets get approved.
We also have settings in Change Advisory Boards tab to fix the minimum number of CAB approvers after which the ticket will be approved.
Unfortunately, there is no such option while rejecting a ticket in CAB.
For rejection of such ticket, all the CAB members have to reject a ticket and then only it gets rejected.
There should be an option for minimum Disapprovers or Reject CAB members, so that it wont cause any unnecessary delays and also isolation of such tickets.