CVE-2017-15042

Name of the Vulnerable Software and Affected Versions Go versions prior to 1.8.4 Go versions 1.9.x prior to 1.9.1

Description An issue exists where the PLAIN authentication scheme is used on network connections not secured with TLS, contrary to the requirements of RFC 4954. This allows a man-in-the-middle SMTP server to obtain the username and password. The smtp.PlainAuth implementation in Go sends the username and password if a man-in-the-middle SMTP server does not advertise STARTTLS but does advertise that PLAIN auth is acceptable.

Recommendations For Go versions prior to 1.8.4, update to version 1.8.4 or later to resolve the issue. For Go versions 1.9.x prior to 1.9.1, update to version 1.9.1 or later to resolve the issue. As a temporary workaround, consider restricting the use of the smtp.PlainAuth function to only secure connections until a patch is applied.