This book constitutes the refereed proceedings of the 19th International Conference on Computational Intelligence in Security for Information Systems, CISIS 2026, held in Marbella, Spain, during June 18–19, 2026.

The 23 full papers included in this volume were carefully reviewed and selected from 49 submissions. The papers cover the following topical sections: Hybrid Security Analytics; Secure AI, and Cryptography & Software Assurance. The papers also include the special session: Artificial Intelligence for Protecting the Internet of Things (AIP-IoT).