UnrealIRCd 3.2.3 allows remote attackers to cause an unspecified denial of service by causing a linked server to send malformed TKL Q:Line commands, as demonstrated by "TKL - q\x08Q *\x08PoC."
https://exchange.xforce.ibmcloud.com/vulnerabilities/25130
http://www.vupen.com/english/advisories/2006/0908
http://www.securityfocus.com/bid/17057
http://www.securityfocus.com/archive/1/427213/100/0/threaded