The remote host is vulnerable to a buffer overflow.
The remote host is running the Trillian IRC client. Trillian versions 0.73, 0.74, and possibly other versions are vulnerable to a buffer overflow, caused by improper validation of Internet Relay Chat (IRC) raw 221 user mode requests. By sending a raw 221 request with a mode of more than 251 bytes, a remote attacker in control of a malicious IRC server could overflow a buffer and cause the victim's Trillian client to crash or execute code on the system.
Upgrade or patch according to vendor recommendations.