In udp mode ncat application doesn't populate environment variables.
Backport of https://github.com/nmap/nmap/commit/e8b73078fd56a4d16ffa9cbb51f43ac75c5f7f1f is needed
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.
For information on the advisory, and where to find the updated
files, follow the link below.
If the solution does not work for you, open a new bug report.