This indicates an attack attempt to exploit a Remote Code Execution Vulnerability in mIRC.
A remote attacker could exploit this vulnerability by enticing a user to open a maliciously crafted link. Successful exploitation could result in execution of arbitrary code under the security context of the application.
mIRC prior to version 7.55
System Compromise: Remote attackers can gain control of vulnerable systems.
Apply the most recent upgrade or patch from the vendor.