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.
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.
An issue was discovered in Irssi before 1.0.4. While updating the internal nick list, Irssi could incorrectly use the GHashTable interface and free the nick while updating it. This would then result in use-after-free conditions on each access of the hash table.