An investigation is being held into how a student was given a copy of the NCEA Level 3 Art History paper four days before the exam took place.
The incident is one of three security breaches recorded during this year's NCEA exam season.
And in another incident a member ofthe public handed in 14 marked Level 1 Science papers which had been left in a Wellington park after being stolen from a marker's letterbox.
NZ Qualification Authority acting chief executive Karen Sewell said a senior public servant had been appointed to carry out an independent investigation into how the Art History student was given the copy of the exam paper.
"I am satisfied that the breach was a genuine human error. I have apologised to the student and their family."
Ms Sewell said she thought the student had been disadvantaged because he or she had thought they were looking at the 2004 paper and had calculated the same questions would not be asked again this year, so had not studied those areas.
"We will carefully monitor the student's results and have sought advice from the school to ensure the student gets a fair and accurate result."
In another security breach, material from a school practice exam appeared in the actual NCEA exam, which Ms Sewell had also ordered an independent investigation into.
"The examiner, a teacher in the school, pre-tested a version of the exam last year, failed to destroy the material as required and it was used again this year by a different teacher in the practice exam."
In a third incident a Te Reo Maori Scholarship paper was mistakenly attached to one Level 1 History paper when the printed papers were being assembled.
The marking of the two million exams are now almost complete, Ms Sewell said. Of the 335 standards being tested this year 16, or 4.7 per cent, were re-marked.
