Modules.cpp in ZNC before 1.7.4-rc1 allows remote authenticated non-admin users to escalate privileges and execute arbitrary code by loading a module with a crafted name.
ZNC before 1.7.1-rc1 does not properly validate untrusted lines coming from the network, allowing a non-admin user to escalate his privilege and inject rogue values into znc.conf.
The CWebAdminMod::ChanPage function in modules/webadmin.cpp in ZNC before 1.4 allows remote authenticated users to cause a denial of service (NULL pointer dereference and crash) by adding a channel with the same name as an existing channel but without the leading # character, related to a "use-after-delete" error.