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Week 1, 2026 security incident report

Hacking and data breach incidents newly reported 2025.12.29 ~ 01.04

New in South Korea4
New elsewhere23
Exposed in South Korea (as announced)900k

Between 29 December 2025 and 4 January 2026, four new cyber-security incidents occurred in South Korea, with the leak of 900,000 personal records at a certified medical institution standing out in terms of stated scale. The leak of personal data of Weverse fan-signing event winners was covered in seven articles, the most of any South Korean incident, and Inha University suffered both a personal data leak and a 14-hour website outage owing to a ransomware attack. Hacking damage at all three of South Korea's mobile operators was also confirmed, with data leaks and breaches occurring across multiple sectors, including healthcare, education, telecoms and fan platforms. Overseas, 23 new incidents occurred, with key cases including the leak of patients' medical records at New Zealand's Manage My Health, the leak of data on 2.4 million WIRED accounts and a ransomware attack on Sedgwick's government contracting subsidiary.

By type

  • Hacking & intrusion9
  • Data breach9
  • Ransomware7
  • Malware1
  • DDoS1

Key incidents in South Korea

Key incidents in other countries