Elasticsearch 5.5.0, based on Lucene 6.6.0, is the latest stable release available for deployment on Elastic Cloud, introducing a security fix for X-Pack Security users and a Windows MSI Installer, which simplifies setup with a graphical user interface. The update addresses a sensitive information leak issue in X-Pack Security, urging users to upgrade to prevent confidential data exposure through the _nodes API. It also includes support for ICU Collation Keyword fields for language-specific sorting, new ip_range field types for IPv6 range indexing, and enhancements to terms aggregations for reduced memory usage, preparing for future changes like the one-type-per-index shift in version 6.0. Users are encouraged to download and provide feedback on the release through social media and the Elastic forum.