Worked on security hardening and reliability improvements for the 1Panel repository, focusing on backend API development using Go. Addressed a critical vulnerability by implementing centralized input validation to prevent command injection across eight API endpoints, including SSH log queries, IPtables rule searches, and database backup operations. Applied secure coding practices and backend development expertise to introduce the CheckIllegal validation, reducing the attack surface while maintaining existing functionality and performance. This work enhanced defense-in-depth and improved audit readiness, ensuring safer handling of untrusted inputs in administrative workflows. Demonstrated skills in API input validation, security best practices, and cross-module backend engineering.