Directory traversal vulnerability in the client in HexChat 2.11.0 allows remote IRC servers to read or modify arbitrary files via a .. (dot dot) in the server name.
https://www.exploit-db.com/exploits/39656/
https://euvd.enisa.europa.eu/vulnerability/EUVD-2016-3192
http://www.securityfocus.com/bid/95881
http://packetstormsecurity.com/files/136564/Hexchat-IRC-Client-2.11.0-Directory-Traversal.html