Software Engineering Institute

According to Microsoft:

An IME is a program that allows computer users to enter complex characters and symbols, such as Japanese characters, using a standard keyboard.
The Microsoft Windows Korean IME contains a vulnerability that may allow an attacker to gain SYSTEM privileges. To exploit this vulnerability, the Korean IME must be installed and the attacker must have access to the Windows login screen.

For more information, including a list of vulnerable systems, please refer to Microsoft Security Bulletin MS06-009.

An attacker may be able to gain SYSTEM privileges on a vulnerable system.

Apply an Update
Microsoft has addressed this issue in Microsoft Security Bulletin MS06-009.

Please see Microsoft Security Bulletin MS06-009 for a list of workarounds to mitigate this vulnerability.