Hi all. It seems that mutt fails to check the validity of a SMTP
servers certificate during a TLS connection. In my mutt configuration
set ssl_starttls = yes
set ssl_force_tls = yes
However, after performing the steps below I found that mutt did not
properly validate the remote servers SMTP tls certificate. This means
that an attacker could potentially MITM a mutt user connecting to
their SMTP server even when the user has forced a TLS connection.
Steps to test this:
1. I set in my hosts file the ip for smtp.gmail.com to be bound to
2.Then I changed my
set smtp_url = "smtp://MYUSERNAME () smtp gmail com:587/"
set smtp_url = "smtp://MYUSERNAME () mail lolok com:587/"
3. I opened up mutt and emailed my self. I note that I saw mutt say
"connecting to mail.lolok.com".
I feel that this is an issue because mutt _does_ actually perform IMAP
server certificate validation (at least it did when I last tested it