irssi: Execution of arbitrary code

Background

irssi is a modular textUI IRC client with IPv6 support.

Description

Nemo discovered an off-by-one error leading to a heap overflow in irssi’s event_wallops() parsing function.

Impact

A remote attacker might entice a user to connect to a malicious IRC server, use a man-in-the-middle attack to redirect a user to such a server or use ircop rights to send a specially crafted WALLOPS message, which might result in the execution of arbitrary code with the privileges of the user running irssi.

Workaround

There is no known workaround at this time.

Resolution

All irssi users should upgrade to the latest version:

 # emerge --sync
 # emerge --ask --oneshot --verbose ">=net-irc/irssi-0.8.13-r1"