mIRC version 6.1 and below on Windows 2000 is susceptible to a buffer overflow attack. If a user is tricked into loading a malicious URL that launches the mirc.exe binary, a remote attacker can overwrite the saved instruction pointer and control the program’s execution.
You can download this advisory from the following link: https://packetstormsecurity.com/files/download/31809/mirc61.txt
Source: https://packetstormsecurity.com/files/31809/mirc61.txt.html