This issue exists to document that a security improvement in the way that Jira Server and Data Center use templates has been implemented. Affected versions of Atlassian Jira Server and Data Center allowed remote attackers with system administrator permissions to execute arbitrary code via Template Injection leading to Remote Code Execution (RCE) in the Email Templates feature. The affected versions are before version 8.13.15 and from version 8.14.0 before 8.20.3.