fetchmail's SMTP client, when configured to authenticate, is
susceptible to a protocol violation where, when a trusted but
malicious or malfunctioning SMTP server responds to an
authentication request with a "334" code but without a following
blank on the line, it will attempt to start reading from memory
address 0x1 to parse the server's SASL challenge. This address is
constant and not under the attacker's control. This event will
usually cause a crash of fetchmail.