This book constitutes the refereed proceedings of the 26th IFIP WG 11.3 International Conference on Data and Applications Security and Privacy, DBSec 2012, held in Paris, France in July 2012. The 17 revised full and 15 short papers presented together with 1 invited paper were carefully reviewed and selected from 49 submissions. The papers are organized in topical sections on access control, confidentiality and privacy, smart cards security, privacy-preserving technologies, data management, intrusion and malware, probabilistic attacks and protection, and cloud computing.