If it's a simple stack overflow or buffer overrun, then given that they're plain binary data packets, it should be pretty easy to exploit.

800 packets/sec x 40 byte/packet = 32 kByte/sec data throughput. Plenty of space for a nice exploit.

Heh, I wonder what happens if one could modify a DOCSIS modem to transmit on a DVB channel - in theory you could compromise an entire house, or worse, an entire block (depending on where the DOCSIS concentrator filters out uplink frequencies) by transmitting a fake DVB-C channel... it might even be better to look for problems in the DVB EPG code, because TV PC software can be better debugged.