IRSSI-SA-2019-08 Irssi Security Advisory 
Use after free when receiving duplicate CAP found by Joseph Bisch. (CWE-416)
CVE-2019-15717  was assigned to this issue.
May affect the stability of Irssi.
- Irssi 1.2.0 and later
Upgrade to Irssi 1.2.2. We’ve published maintenance releases, without any new features.
After installing the updated packages, one can issue the /upgrade command to load the new binary. TLS connections will require /reconnect.
Most servers do not send duplicate CAP