WinSCP before 5.5.3, when FTP with TLS is used, does not verify that the server hostname matches a domain name in the subject's Common Name…

WinSCP before 5.5.3, when FTP with TLS is used, does not verify that the server hostname matches a domain name in the subject's Common Name (CN) or subjectAltName field of the X.509 certificate, which allows man-in-the-middle attackers to spoof SSL servers via an arbitrary valid certificate.