The four-volume set LNCS 14344-14347 constitutes the refereed proceedings of the 28th European Symposium on Research in Computer Security, ESORICS 2023, which took place in The Hague, The Netherlands, during September 25-29, 2023. The 93 full papers presented in these proceedings were carefully reviewed and selected from 478 submissions. They were organized in topical sections as follows:Part I: Crypto. Part II: Network, web and internet; privacy; and remote. Part III: Attacks; blockchain; and miscellaneous. Part IV: Machine learning; software and systems security.