This book constitutes the refereed proceedings of the 41st IFIP International Conference on ICT Systems Security and Privacy Protection, SEC 2026, held in Perth, Australia, during June 9&11, 2026. The 39 full papers included in this book were carefully reviewed and selected from 164 submissions. They were organized in topical sections as follows: AI for Cyber Security; Cryptography; Cyber-Physical Systems Security; Data and Applications Security; Network and Systems Security; Privacy, Identification, Authentication and Access Control.