"Obviously, your quickest and surest fix is going to be
disabling SNMP if you don't have to run it. Indeed, disabling
unnecessary network services is a normal part of system hygeine, so
this is a good opportunity to take the time and do a thorough job
of it.
If you're stuck with it, then you can filter ports 7/udp 161/udp
161/tcp 162/udp 162/tcp 199/udp 199/tcp 391/udp 391/tcp 705/tcp
1993/udp and 1993/tcp. Obviously, if you need to keep any of these
open you'll leave a vulnerability, but by shutting off the ones you
don't need you'll make it easier to monitor for suspicious
activity.
Meanwhile, check with your vendor for specific advice and patch
availability relevant to your router/switch/hub/server/OS/etc. All
the vendors are currently working on patches, and it may be only a
matter of hours before yours makes one available if it hasn't yet.
The most comprehensive single source of general information and
workaround suggestions is the CERT Advisory."
