The Authorize.Net eCheck module in Zen Cart 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.
Exploitability
AV:NAC:MAu:NImpact
C:PI:PA:N5.8/AV:N/AC:M/Au:N/C:P/I:P/A:N