An issue was discovered in Irssi before 1.0.7 and 1.1.x before 1.1.1. There is a use-after-free when a server is disconnected during netsplits. NOTE: this issue exists because of an incomplete fix for CVE-2017-7191.
http://openwall.com/lists/oss-security/2018/02/15/1
https://usn.ubuntu.com/3590-1/