The NZEI is calling for a full public inquiry into what it calls 'the Novopay debacle'.
Security breaches are the latest revelations in a long list of calamities since the Novopay system was introduced three months ago.
The $30 million Novopay system has left hundreds of teachers across New Zealand either short-paid, or not paid at all.
NZEI National Secretary Paul Goulter says there needs to be a full inquiry to find out the cause of the fiasco, who is responsible, and how it can be fixed so the problems never happen again.
Mr Goulter says Novopay has caused endless stress for schools and staff for months and it needs to be fixed immediately.