Worked on security hardening for XML content handling in the Zimbra/zm-mailbox repository, focusing on reducing XML-based XSS risks across mail, calendar, and related user interfaces. Implemented extended sanitization to cover all +xml content types, updated defang logic for broader MIME-type coverage, and enhanced LC configuration to enable these changes through configuration management. Leveraged Java and XML handling expertise, applying security best practices to strengthen defense-in-depth for user-rendered content. The work emphasized maintainability and future extensibility, with clear commit documentation and review-driven refinements, resulting in improved security posture and minimal deployment impact for the Zimbra/zm-mailbox codebase.