ircu 2.10.12.03 and 2.10.12.04 does not associate a timestamp with ops privilege on an unused channel (zannel), which allows remote attackers to (1) set or remove certain channel modes via a "netriding" attack or (2) take over a channel by joining an unlinked server with the A/Upass and then setting a new Apass.
https://exchange.xforce.ibmcloud.com/vulnerabilities/35989
http://www.securityfocus.com/archive/1/476285/100/0/threaded