CVE-2019-6110 identifies an output manipulation vulnerability in OpenSSH 7.9's SCP client that enables malicious servers or man-in-the-middle attackers to manipulate client terminal output through arbitrary stderr content injection. This vulnerability achieves a CVSS score of 6.8 (Medium severity) with an EPSS score of 97.6 percentile and 48.5% exploitation probability, indicating significant attack potential for scenarios involving untrusted SSH servers or compromised network connections. The vulnerability details reveal that the SCP client accepts and displays arbitrary stderr output from remote servers without proper sanitization, allowing attackers to inject ANSI control codes that can hide additional file transfers, manipulate progress displays, or deceive users about the actual operations being performed. This creates substantial exploit risk for users connecting to untrusted SSH servers, particularly affecting secure file transfer operations, automated backup systems, and enterprise environments where SCP is used for critical data synchronization between potentially compromised or malicious remote hosts. The technical root cause lies in OpenSSH's SCP client implementation within scp.c, specifically in the response() and error() functions that process and display server-originated stderr messages without proper sanitization, classified as CWE-838 (Inappropriate Encoding for Output Context), creating a vector for known exploited vulnerabilities targeting terminal manipulation attacks. The vulnerability specifically affects the interaction between the SCP client's main() orchestration logic and stderr handling mechanisms, where malicious servers can send crafted ANSI escape sequences through stderr that manipulate terminal display, hide file transfer activities, or present false information to users about ongoing operations. With public exploits available and affecting NixOS, WinSCP, and over 9 other technologies including pam_ssh_agent_auth, this vulnerability demonstrates the importance of proper output sanitization in secure shell applications. Mitigation strategies include upgrading to OpenSSH versions after 7.9 that implement proper stderr sanitization and ANSI code filtering, configuring terminal environments to restrict ANSI escape sequence processing during SCP operations, and implementing strict validation for remote server authenticity before file transfer operations. Organizations should prioritize identifying all systems using vulnerable OpenSSH versions, implement additional verification mechanisms for file transfer operations, educate users about the risks of connecting to untrusted SSH servers, and maintain updated CVE database records to track similar output manipulation vulnerabilities that could compromise secure communication integrity through terminal display manipulation and user deception attacks in SSH-based file transfer systems.