Mozilla: Downgrade attack on SMTP STARTTLS connections

Thunderbird ignored the configuration to require STARTTLS security for an SMTP connection. A MITM could perform a downgrade attack to intercept transmitted messages, or could take control of the authenticated session to execute SMTP commands chosen by the MITM. If an unprotected authentication...

Mozilla: Security downgrade with IMAP STARTTLS leads to information leakage

The Mozilla Foundation Security Advisory describes this flaw as: If Thunderbird is configured to use STARTTLS for an IMAP server, and the server sends a PREAUTH response, then Thunderbird will continue with an unencrypted connection, causing email data to be sent without protection...