In Irssi before 1.0.5, certain incorrectly formatted DCC CTCP messages could cause a NULL pointer dereference. This is a separate, but similar, issue relative to CVE-2017-9468.

In Irssi before 1.0.5, overlong nicks or targets may result in a NULL pointer dereference while splitting the message.

In certain cases, Irssi before 1.0.5 may fail to verify that a Safe channel ID is long enough, causing reads beyond the end of the string.

Irssi before 1.0.5, while waiting for the channel synchronisation, may incorrectly fail to remove destroyed channels from the query list, resulting in use-after-free conditions when updating the state later on.

Irssi before 1.0.5, when installing themes with unterminated colour formatting sequences, may access data beyond the end of the string.