There are mainly 3 statuses. They are as follows:

Accept, Reject, Deffered.

When a developer accepts to fix the reported bug, then the developer changes the status of the bug, from Assigned to Accepted.

When a developer doesn't accept the bug, he gives the status Rejected. But the developer needs to give a valid reason to reject the bug.

When a developer and his superiors think that the bug cannot be fixed in this release(due to lack of time or required documentation) then the developer gives the Deffered status. The developer needs to specify when the bug will be fixed.