When using incomplete escape codes, Irssi before 1.0.6 may access data beyond the end of the string.

In Irssi before 1.0.6, a calculation error in the completion code could cause a heap buffer overflow when completing certain strings.

When the channel topic is set without specifying a sender, Irssi before 1.0.6 may dereference a NULL pointer.

When using an incomplete variable argument, Irssi before 1.0.6 may access data 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.

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

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

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 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.

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.