This book constitutes the refereed proceedings of the 26th International Conference on Information Security Applications, WISA 2025, held in Jeju Island, South Korea, during August 20–22, 2025.

The 26 full papers included in this book were carefully reviewed and selected from 66 submissions. They were organized in topical sections as follows: System & Application Security, 5G & Network Security, Cybersecurity Education & Model Security, Security Analysis & Verification, Malware & Forensics, Quantum & Cryptography, AI/LLM for Security, Privacy & Anonymity and IoT & Traffic Analysis.