ircu 2.10.12.05 and earlier ignores timestamps in bounces, which allows remote attackers to take over a channel during a netjoin by causing a bounce while a server with an older version of the channel is linking.
https://exchange.xforce.ibmcloud.com/vulnerabilities/35994
https://euvd.enisa.europa.eu/vulnerability/EUVD-2007-4391
http://www.securityfocus.com/bid/25285
http://www.securityfocus.com/archive/1/476285/100/0/threaded