source: http://www.securityfocus.com/bid/35399/info

Irssi is prone to an off-by-one, heap-based, memory-corruption vulnerability because it fails to properly bounds-check user-supplied data before copying it into a memory buffer.

Attackers can exploit this issue to crash the vulnerable client, resulting in a denial-of-service condition. Given the nature of this issue, attackers may also be able to run arbitrary code within the context of the vulnerable application, but this has not been confirmed.

Iirssi 0.8.13 is vulnerable; other versions may also be affected. 

The following example IRC command is available; please see the references for more information.

: WALLOPS \001ACTION