irssi was updated to fix four vulnerabilities that could result in denial 
of service (remote crash) when connecting to malicious servers or receiving
specially crafted data. (boo#1018357)

- CVE-2017-5193: NULL pointer dereference in the nickcmp function
- CVE-2017-5194: out of bounds read in certain incomplete control codes
- CVE-2017-5195: out of bounds read in certain incomplete character sequences 
- CVE-2017-5196: Correct an error when receiving invalid nick message