CVE-2020-12063

DISPUTED A certain Postfix 2.10.1-7 package could allow an attacker
to send an email from an arbitrary-looking sender via a homoglyph attack,
as demonstrated by the similarity of \xce\xbf to the ‘o’ character. This is
potentially relevant when the /etc/postfix/sender_login feature is used,
because a spoofed outbound message that uses a configured sender address is
blocked with a “Sender address rejected: not logged in” error message, but
a spoofed outbound message that uses a homoglyph of a configured sender
address is not blocked. NOTE: some third parties argue that any missed
blocking of spoofed outbound messages - except for exact matches to a
sender address in the /etc/postfix/sender_login file - is outside the
design goals of Postfix and thus cannot be considered a Postfix
vulnerability.

Notes