nse_libssh2.cc in Nmap 7.70 is subject to a denial of service condition due to a double free when an SSH connection fails, as demonstrated by a leading \n character to ssh-brute.nse or ssh-auth-methods.nse.
https://seclists.org/nmap-dev/2018/q2/45
https://seclists.org/nmap-announce/2019/0
https://github.com/nmap/nmap/issues/1077
https://github.com/nmap/nmap/commit/350bbe0597d37ad67abe5fef8fba984707b4e9ad
https://github.com/AMatchandaHaystack/Research/blob/master/Nmap%26libsshDF
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00075.html
http://lists.opensuse.org/opensuse-security-announce/2019-09/msg00073.html