The Malaysia meeting was a major planning session for 9/11 and was held from 5-8 January 2000 and attended by various al-Qaeda operatives, some of whom went on to participate in the operation. The CIA and NSA found out about it in advance by tapping one of the hijackers’ phones, so it was also surveilled by Malaysian intelligence and the results were passed to the CIA. However, no complete list of the attendees has ever been published.

In his book Intelligence Matters, Bob Graham, co-chairman of the 9/11 Congressional Inquiry, makes the following claim:

One of the organizers of the failed attack ((on the USS Sullivans)) was Muhammad Omar al-Harazi, an al-Qaeda operations chief in East Africa and one of the plotters of the Nairobi embassy bombing. Al-Harazi was personally humiliated by the failed attack. Two days later, he headed to Kuala Lumpur for the terrorist summit that the CIA knew was taking place. (p. 59)

Graham seems pretty solid as a source to me, so we can add al-Harazi to the other 6 generally accepted attendees (the total is supposed to be 13):
(1) Khalid Almihdhar, American 77 hijacker;
(2) Nawaf Alhazmi, American 77 hijacker;