An issue was discovered in Irssi before 1.0.4. When receiving messages with invalid time stamps, Irssi would try to dereference a NULL pointer.
https://www.debian.org/security/2017/dsa-4016
https://irssi.org/security/irssi_sa_2017_07.txt
https://github.com/irssi/irssi/commit/5e26325317c72a04c1610ad952974e206384d291