CVE-2019-14664

In Enigmail below 2.1, an attacker in possession of PGP encrypted emails
can wrap them as sub-parts within a crafted multipart email. The encrypted
part(s) can further be hidden using HTML/CSS or ASCII newline characters.
This modified multipart email can be re-sent by the attacker to the
intended receiver. If the receiver replies to this (benign looking) email,
he unknowingly leaks the plaintext of the encrypted message part(s) back to
the attacker. This attack variant bypasses protection mechanisms
implemented after the “EFAIL” attacks.