Irssi 1.3.x and 1.4.x before 1.4.4 has a use-after-free because of use of a stale special collector reference. This occurs when printing of a non-formatted line is concurrent with printing of a formatted line.

Irssi 1.2.x before 1.2.2 has a use-after-free if the IRC server sends a double CAP.

Irssi before 1.0.8, 1.1.x before 1.1.3, and 1.2.x before 1.2.1, when SASL is enabled, has a use after free when sending SASL login to the server.

Irssi 1.1.x before 1.1.2 has a use after free when hidden lines are expired from the scroll buffer.

An issue was discovered in Irssi before 1.0.7 and 1.1.x before 1.1.1. There is a use-after-free when a server is disconnected during netsplits. NOTE: this issue exists because of an incomplete fix for CVE-2017-7191.

An issue was discovered in Irssi before 1.0.7 and 1.1.x before 1.1.1. There is a use-after-free when SASL messages are received in an unexpected order.

An issue was discovered in Irssi before 1.0.7 and 1.1.x before 1.1.1. When the number of windows exceeds the available space, a crash due to a NULL pointer dereference would occur.

An issue was discovered in Irssi before 1.0.7 and 1.1.x before 1.1.1. A NULL pointer dereference occurs for an "empty" nick.

An issue was discovered in Irssi before 1.0.7 and 1.1.x before 1.1.1. Certain nick names could result in out-of-bounds access when printing theme strings.

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