ZNC is an advanced IRC bouncer.
ZNC's modtcl could allow for remote code execution via a KICK.
A vulnerable ZNC with the modtcl module loaded could be exploited for remote code execution.
Unload the mod_tcl module.
All ZNC users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=net-irc/znc-1.9.1"