The Cisco Security Advisory clearly says:
This vulnerability exists whether the device is configured in Router mode or Gateway mode.
So the problem will still exist whether or not you're in bridge mode. If you use your own private router, at least you're putting a firewall between you and the modem. However, the modem can still be taken over completely by the bad guys. If they do that, then your connection to the internet is at the mercy of very evil people. This is in stark contrst to the current situation where your connection to the internet is at the mercy of Rogers.