An issue was discovered in Mutt before 1.10.1 and NeoMutt before 2018-07-16. imap/util.c mishandles ".." directory traversal in a mailbox name.
https://www.debian.org/security/2018/dsa-4277
https://usn.ubuntu.com/3719-3/
https://security.gentoo.org/glsa/201810-07
https://neomutt.org/2018/07/16/release
https://lists.debian.org/debian-lts-announce/2018/08/msg00001.html
https://gitlab.com/muttmua/mutt/commit/31eef6c766f47df8281942d19f76e35f475c781d
https://github.com/neomutt/neomutt/commit/57971dba06346b2d7179294f4528b8d4427a7c5d