The format_send_to_gui function in formats.c for irssi before 0.8.9 allows remote IRC users to cause a denial of service (crash).
https://exchange.xforce.ibmcloud.com/vulnerabilities/13973
http://www.securityfocus.com/archive/1/347218
http://www.mandriva.com/security/advisories?name=MDKSA-2003:117