unstable: high cpu usage by /sbin/urngd

Hi all, getting a lot of instability. On MacOS Mojave, running Docker version 19.03.8, and docker-machine version 0.16.2

If I just use the Readme command:

docker run --rm -it openwrtorg/rootfs

I get a number of error messages during launch:

rich$ docker run --rm -it openwrtorg/rootfs
Failed to resize receive buffer: Operation not permitted
ip: RTNETLINK answers: Operation not permitted
Press the [f] key and hit [enter] to enter failsafe mode
Press the [1], [2], [3] or [4] key and hit [enter] to select the debug level
ip: can't send flush request: Operation not permitted
ip: SIOCSIFFLAGS: Operation not permitted
Please press Enter to activate this console.

When in the shell, it's sluggish, and I notice that one core of my CPU is being used at 100%. A top inside the container reveals the following:

Mem: 433964K used, 579256K free, 290552K shrd, 9536K buff, 323160K cached
CPU:  99% usr   0% sys   0% nic   0% idle   0% io   0% irq   0% sirq
Load average: 0.99 0.58 0.24 2/163 817
  PID  PPID USER     STAT   VSZ %VSZ %CPU COMMAND
   92     1 root     R      780   0% 100% /sbin/urngd
  279     1 root     S     1300   0%   0% /sbin/rpcd -s /var/run/ubus.sock -t 30
  434     1 root     S     1196   0%   0% /sbin/netifd
    1     0 root     S     1116   0%   0% /sbin/procd
   76     1 root     S     1084   0%   0% /bin/ash --login

Am I doing something wrong?

Start by reproducing the README command docker run --rm -it openwrtorg/rootfs on the reported macOS and Docker versions, then inspect the /sbin/urngd process shown by top. Compare the reported permission errors and CPU behavior with a working environment; done means identifying whether the issue is in the container or host setup and documenting the cause or next diagnostic step.