source: http://www.securityfocus.com/bid/22846/info

SILC Server is prone to a denial-of-service vulnerability because the application fails to handle exceptional conditions.

An attacker can exploit this issue to crash the affected server, effectively denying service to legitimate users.

This issue affects version 1.0.2; other versions may also be affected.

The following proof of concept demonstrates this issue:

connect yourserver
join nonexistent -hmac nonexistent