The astonishingly frank admission came in a statement to the Parliament last week as schools and authorities across the country report growing difficulties with recruitment.
Jack McConnell, the Education Minister, promised action to identify more accurate ways to assess future needs following the post-McCrone agreement to boost staffing.
An Executive spokeswoman accepted there were "certain shortages in certain subjects in certain areas". But the Executive's analysis makes it clear that difficulties will continue. "The blind spot in the current approach is that it does not address the issue of the current teaching stock relevant to demand," it says.
"As a result there is no focused current information on what is happening in relation to the supply of teachers; there is currently no reliable information on teacher vacancies by subject; nor do we have accurate information on how long a vacancy has existed. The result of all this is that we are unable to project the minimum requirements for newly qualified teachers by subject or location."
The Executive says most local authority infomation does not include hard statistics. "We are not aware through official channels of vacancies for permanent posts generally remaining unfilled in any quantity."
Priority subjects in terms of supply cover can vary from authority to authority, the Executive says, and can include subjects not on the current list.
"Education authorities have reported difficulty in undertaking projections on the subjects in which they are likely to have difficulty recruiting teachers. There have been no formal representations from EAs about difficulties in recruiting in specific subjects."
Five authorities - Edinburgh, Fife, Stirling, Glasgow and the Western Isles - are involved in a pilot with the Executive to provide six-monthly details in greater depth.
South of the border, ministers have already sanctioned financial incentives such as pound;6,000 training salaries and pound;4,000 golden hellos for priority subjects. Now, for the first time, the Executive says "this position will be kept under review".
Ivor Sutherland, registrar of the General Teaching Council for Scotland, awarded "full marks" to the Executive for at last trying to get on top of the problem.
But John Mulgrew, president of the Association of Directors of Education in Scotland, said criticism of the authorities' projections was "amazing". "If there is a new national strategy, we will be happy to co-operate."