Magento Commerce and Open Source 2.3.1, 2.2.8 and 2.1.17 contain multiple security enhancements that help close Remote Code Execution (RCE), Cross-Site Scripting (XSS) and other vulnerabilities.

https://magento.com/security/patches/magento-2.3.1-2.2.8-and-2.1.17-security-update