This book constitutes the refereed proceedings of the 11th International Conference on Code-Based Cryptography, CBCrypto 2023, held in Lyon, France, during April 22–23, 2023. The 8 full papers included in this book were carefully reviewed and selected from 28 submissions. The conference offers a wide range of many important aspects of code-based cryptography such as cryptanalysis of existing schemes, the proposal of new cryptographic systems and protocols as well as improved decoding algorithms.