ZNC 1.0 allows remote authenticated users to cause a denial of service (NULL pointer reference and crash) via a crafted request to the (1) editnetwork, (2) editchan, (3) addchan, or (4) delchan page in modules/webadmin.cpp.
ZNC before 1.7.3-rc1 allows an existing remote user to cause a Denial of Service (crash) via invalid encoding.