A flaw was found in libnbd. An assertion failure in in nbd_unlocked_opt_go in ilb/opt.c may lead to denial of service.
It's really all Eric's work, I just tested his patch.
Name: Eric Blake (Red Hat)
Red Hat Enterprise Linux 8 is not affected by this issue. The affected API was introduced in upstream `libnbd` version 1.4 which is only shipped in RHEL Advanced Virtualization 8.3.0 onward.