Magento Open Source 2.2.3, 2.1.12, and 2.0.18 include critical security enhancements and feature updates, including support for recent USPS API changes. Review the release notes for more information: http://devdocs.magento.com/guides/v2.2/release-notes/ReleaseNotes2.2.3CE.html, http://devdocs.magento.com/guides/v2.1/release-notes/ReleaseNotes2.1.12CE.html, http://devdocs.magento.com/guides/v2.0/release-notes/ReleaseNotes2.0.18CE.html  
