The Hong Kong Examinations and Assessment Authority said personal information belonging to about 16,900 mainland-resident applicants for two international examinations was exposed.
The authority said the affected system was used for certain small-scale international examinations. It said there was no evidence that the Diploma of Secondary Education Examination or most other international examinations had been affected.
The authority said it discovered the incident on Thursday, 29 October, and reported it to police. It also notified the personal-data privacy regulator and relevant examination organisers. The cause and full scope are under investigation. The authority is following up on arrangements to notify affected applicants.
Applicants can enquire by calling 3628 8787 or emailing ie@hkeaa.edu.hk.