The specific flaw exists within the gwwww1.dll module responsible for parsing VCALENDAR data within e-mail messages. When the code encounters a TZNAME variable it allocates up to 0xFFFF bytes for the variable's value. It then proceeds to copy the value into the fixed-length buffer without checking if it will fit. By specifying a large enough string in the e-mail, an attacker can overflow the buffer and execute arbitrary code under the context of the SYSTEM user.
