@Brian81,
The defect you listed was in regards to SEP misidentifying UDP traffic from a DNS server to be a UDP flood. Whatever changes were implemented to address the issue in RU6 MP1 were made to address this issue in regards to DNS servers specifically and were not made to address any UDP flood false positive detections which might occur from network printers.
@kornholio,
I've seen situations before where printers will trigger Denial of Service rules in SEP even when they are working normally. The printers just happen to communicate in a way which triggers our DoS rules.
A good short-term solution would be, as Brian81 suggested, to add the printer to the list of excluded hosts. Admittedly, the chances of your printer sending out malicious traffic or being infected is very small, but best practices would have you only exclude the printer if you know that the traffic from the printer is non-malicious.
Unfortunately, determining whether or not the traffic is malicious is not something I can assist with as I do not have the means to know what normal printer traffic for your printer should look like. You may consider gathering a packet capture of the traffic which is triggering the DoS detection and opening a support ticket with the maker of the printer in order to determine if the traffic is malicious. If it is not malicious, exclude the printer as a workaround. You could then open a Symantec Support ticket if you wanted to have us analyze the traffic to determine if we need to change our UDP Flood DoS rules.
Regards,
James