hook.c in BitchX 1.1-final allows remote IRC servers to execute arbitrary commands by sending a client certain data containing NICK and EXEC strings, which exceeds the bounds of a hash table, and injects an EXEC hook function that receives and executes shell commands.
https://www.exploit-db.com/exploits/4087
https://exchange.xforce.ibmcloud.com/vulnerabilities/34969
http://www.securityfocus.com/bid/24579
http://slackware.com/security/viewer.php?l=slackware-security&y=2009&m=slackware-security.285737
http://secunia.com/advisories/34870