Is there a fix ?
Possibly. For some people. There is a firmware that addresses the latency spikes and detects and mitigates the DoS. This firmware has only been rolled out to a small number of devcies on a limited number of ISPs. There is however a new "Packet of death" bug that causes the modem to reboot. This is unaddressed and new firmware will again be needed.
There have been 2 firmware releases. The last one is still being rolled out to some customers. The newest firmware update is also being rolled out to some customers.
First firmware update made the 300ms spike in latencey every 2 second disappear from ICMP and Ping testing. The spike still was present in TCP/UDP. Many feel this was a attempt to hide the issue
The second firmware update DID improve things. It fixed DNS lookups. Previous to this the Puma caused a 7-15% total loss of DNS lookups. So this update did help performance but did not address the spike or high jitter at all.
The third firmware update addressed the 200ms latency spikes ever 2 seconds and had a detection and blocking of the DoS attack but did not fix the underlying issue.