A woman was arrested on Thursday after one of this year's DSE exam papers was posted on social media.
Questions for the English listening exam were said to have been uploaded to Xiaohongshu.
Police said a 23-year-old woman is suspected of violating the Hong Kong Examinations and Assessment Authority Ordinance.
The authority said it is following up on cases involving exam papers being made available publicly, but it believes the leaks only occurred after the exams in question had already taken place.
"Initial findings indicate that the cases involving the online posting of DSE examination papers occurred after the completion of the respective subject examinations. Therefore, the confidentiality of the DSE has not been affected," it said in a statement.
The authority reminded examination staff not to reproduce or publish the content of exam papers in any form.