An issue was discovered in Mutt before 1.10.1 and NeoMutt before 2018-07-16. They have a buffer overflow via base64 data.
www.mutt.org/news.html
github.com/neomutt/neomutt/commit/6f163e07ae68654d7ac5268cbb7565f6df79ad85
gitlab.com/muttmua/mutt/commit/3d9028fec8f4d08db2251096307c0bbbebce669a
lists.debian.org/debian-lts-announce/2018/08/msg00001.html
neomutt.org/2018/07/16/release
security.gentoo.org/glsa/201810-07
usn.ubuntu.com/3719-1/
usn.ubuntu.com/3719-2/
usn.ubuntu.com/3719-3/
www.debian.org/security/2018/dsa-4277