[Chunghwa Security] Supplemental Announcement on the Change of Chairman

1. Date of the board of directors resolution or date of occurrence of the change: June 15, 2026 2. Personnel type (Chairman or General Manager): Chairman 3. Name of the previous position holder: Chen Ming-shih 4. Resume of the previous position holder: Chairman of Chunghwa Telecom Security Co., Ltd. 5. Name of the new position holder: None 6. Resume of the new position holder: Not applicable 7. Type of the change: Retirement 8. Reason for the change: Change of representative by the corporate director 9. Effective date of the new appointment: Not applicable 10. Any other matters that need to be specified: The company received a letter regarding the change of corporate representative from Chunghwa Telecom Co., Ltd. on June 15, 2026. The former representative will retire on June 29, and the new representative will take office on June 30, 2026. Name of the new representative: Huang Chih-hsiung; Resume of the new representative: Executive Vice President and Chief Technology Officer of Chunghwa Telecom Co., Ltd. The new Chairman will be elected at a board meeting to be convened in the near future and will be announced separately.