Is there a fix ?
NO. Not currently. I will update this when there is.
There have been 2 firmware releases. The last one is still 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.
There is no known firmware that fixes the spike or fixes the 0-day DoS attack.
The current state of all Intel Puma based modems is shown in this video. This is with the latest released version of the firmware for all devices.